why can hydrogen be placed in either group 1 or group 7 ?
Hydrogen resembles alkali metals i.e. Li , K , Na , K, Rb ,Cs and Fr of group 1 of the periodic table.
1) Electronic configuration : Like alkali metals, hydrogen also contains 1 electron in its outermost shell.
Hydrogen 1s1
Lithium 1s2 2s1
Sodium 1s2 2s2 2p6 3s1
2) Electropositive character: Like alkali metals ,hydrogen also loses its only electron to form hydrogen ion i.e. H+
H ——-> H+ + e‾
Na ———-> Na+ + e‾
Hydrogen like alkali metals exhibit electropositive character.
3) Oxidation State: Like alkali metals, hydrogen exhibits an oxidation state of +1 in its compounds.
H+ Cl‾
Na+ Cl‾
4) Combination with electronegative elements or non metals: Like alkali metals, hydrogen combines with electronegative elements such as oxygen ,halogen and sulphur forming their oxides ,halides and sulphide.
Oxides H2O like Na2O , K2O
Halides HCl like NaCl , KCl
Sulphides H2S like Na2S , K2S
5) Liberation at the cathode : When an aqueous solution of HCl is electrolysed H2 is liberated at the cathode in the same way as alkali metals are liberated at cathode during the electrolysis of their fused halides.
6)Reducing character: Like alkali metals, hydrogen also act as a strong reducing agent.
Fe2O3 + 4 H2 ———> 3Fe + 4H2O
B2O3 + 6 K ————–> 2B + 3 K2O
SIMILARITY with halogens
Hydrogen resemble halogens i. F , Cl, Br , I of group 17 of the periodic table in the following ways:
1) Electronic configuration: All the halogens have 7 electron in their respective outermost shell and thus have one electron less than the stable configuration of the nearest inert gas. Hydrogen has one electron in the outermost shell and thus has one electron less than the stable configuration of the nearest inert gas i.e. helium.
H 1s1 one electron less than He
F 1s2 2s2 2p5 one electron less than Ne 1s2 2s2 2p6
2) Electronegative character: Halogens have a strong tendency to gain one electron to form halide ions. Hydrogen show some tendency to gain one electron to form hydride ions.
H + e‾ ————-> H‾
Cl + e‾ —————-> Cl‾
3) Ionization enthalpy : Ionization enthalpy of hydrogen is quite compatible with those of halogens but much higher than those of alkali metals.
4) Oxidation State: Just like halogens, hydrogen shows an oxidation state of -1.
5)Liberation at the anode: When fused alkali metal hydrides such as Lithium, sodium hydride is subjected to electrolysis ,hydrogen is liberated at the anode. Similarly halogens are liberated at the anode when fused alkali metal halides are electrolysed.
2NaH ( l ) ————> H2 ( g ) + 2Na ( l )
2 NaCl ( l ) ————–> Cl2 ( g ) + 2Na ( l )
6) Atomicity and non metallic character: Just like halogens, hydrogen also exist as a diatomic molecule. Like halogens, hydrogen is a typical non metal.
7) Combination with metals: Hydrogen combines with highly electropositive alkali and alkaline earth metals to form metallic hydrides. Halogens combine with these metals to form metallic halides.
2Na + H2 ——-> 2NaH
Ca + H2 ——–> CaH2
8) Formation of covalent compounds: Hydrogen readily combines with non-metals such as carbon, Silicon ,nitrogen to form covalent compounds.
CH4 , SiH4 , NH3 , CCl4 , SiCl4
9) Replacement or substitution reaction: In many compounds of carbon ,hydrogen can be replaced by halogens and halogens can be replaced by hydrogen.
CH4 + Cl2 ——-> CH3Cl + HCl
CH3Cl + 2 [H] ——–> CH4 + HCl
On a night when the moon rises at 9 pm, what is its phase?
If the moon rises at 9 pm, the lunar phase will be waxing cresent, the 75% of moon is appearable.
Lunar Phase:
It is the degree of apperance of moon in a cycle of 29.5 days. The moon appears to increase in the first half of the cycle and then decrease in the second half of the cycle.
The moon appears more as its time of rise is increase.
Therefore, if the moon rises at 9 pm, the lunar phase will be waxing cresent, the 75% of moon is appearable.
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Select the correct answer.
Disturbances inside Earth’s core cause earthquakes. The starting point of the disturbance is called the epicenter. Why does the amplitude of a seismic wave usually decrease as the wave moves away from the epicenter?
A) The waves lose energy in the form of heat.
B) The frequency of the waves continues to increase.
C) The wavelength of the waves continues to decrease.
D) The waves encounter entirely different mediums.
When a wave travels through a material, it loses a small amount of energy as heat. Eventually, the wave will stop when it loses all of its energy.
I think the answer is A.
The amplitude of a seismic wave usually decrease as the wave moves away from the epicenter because the waves lose energy in the form of heat. The correct option is A.
What is an Amplitude of wave?It is the maximum distance from the mean position of the wave.
The amplitude of the seismic waves continues to decrease with distance because waves keeps on spreading in the larger portion of area and dissipates heat.
Therefore, the amplitude of a seismic wave usually decreases when the wave moves away from the epicenter because the waves lose energy in the form of heat. The correct option is A.
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A mass m attached to a horizontal massless spring with spring constant k, is set into simple harmonic motion. its maximum displacement from its equilibrium position is
a. what is the masses speed as it passes through its equilibrium position?
The speed of a mass m attached to a spring with spring constant k as it passes through the equilibrium position is given by the equation v = √{(k/m) [tex]\\cdot A^2[/tex]}, where A is the amplitude of the motion.
When a mass m attached to a horizontal massless spring with spring constant k undergoes simple harmonic motion (SHM), the speed of the mass at the equilibrium position can be determined using energy conservation principles. At maximum displacement, the entire energy of the system is potential energy stored in the spring, which is U = 1/2 k [tex]A^2[/tex], where A is the amplitude of motion.
When the mass passes through the equilibrium point, all the potential energy is converted into kinetic energy, KE = 1/2 m [tex]v^2[/tex]. By setting these two energies equal, we get 1/2 k [tex]A^2[/tex] = 1/2 m [tex]v^2[/tex]. This allows us to solve for the velocity, v, as the mass passes through equilibrium:
v = √{(k/m) [tex]\\cdot A^2[/tex]}.
The velocity at the equilibrium point is the maximum speed of the mass during its motion.
The maximum displacement of the spring is the amplitude A and the maximum speed, occurring at the equilibrium position, is given by option b)[tex]v_{\text{max}} = A \sqrt{\frac{k}{m}}[/tex]
A mass m attached to a horizontal massless spring with spring constant k undergoes simple harmonic motion. The maximum displacement from the equilibrium position is the amplitude A. To find the speed of the mass as it passes through its equilibrium position, we use the principle of conservation of energy.
In simple harmonic motion, the total mechanical energy is conserved and is the sum of kinetic energy (KE) and potential energy (PE). At the equilibrium position, the potential energy is zero, and all the energy is kinetic.
The total energy at maximum displacement (x = A) is given by the potential energy:
[tex]PE_{\text{max}} = \frac{1}{2} k A^2[/tex]
At the equilibrium position (x = 0), this energy converts to kinetic energy:
[tex]KE_{\text{max}} = \frac{1}{2} m v_{\text{max}}^2[/tex]
Setting PEmax equal to KEmax:
[tex]\frac{1}{2} k A^2 = \frac{1}{2} m v_{\text{max}}^2[/tex]
Solving for the maximum velocity vmax:
[tex]v_{\text{max}} = A \sqrt{\frac{k}{m}}[/tex]
Therefore, the speed of the mass as it passes through its equilibrium position is [tex]A \sqrt{\frac{k}{m}}[/tex] and the correct option is b).
Complete question is - A mass m attached to a horizontal massless spring with spring constant k, is set into simple harmonic motion. its maximum displacement from its equilibrium position is?
a. what is the masses speed as it passes through its equilibrium position? (A) 0 (B) A√(k/m) (C) A√(m/k) (D) 1/A√(k/m) (E) 1/A√(m/k)
When skydiver nellie opens her parachute, the air drag pushing the chute upward is stronger than earth's force of gravity pulling her downward. a friend says this means she should start moving upward?
Does anyone know the Formula for Law of Inertia?
It's important to remember that the Law of Inertia itself doesn't have a specific formula. It's a qualitative statement about the tendency of objects to resist changes in their state of motion.
However, there are two related concepts that do have formulas:
Newton's Second Law of Motion: This law relates the force applied to an object, its mass, and its resulting acceleration. It can be expressed as F = ma, where:
F is the net force acting on the object (measured in Newtons)
m is the mass of the object (measured in kilograms)
a is the acceleration of the object (measured in meters per square second)
This law is closely related to the Law of Inertia because it explains how the resistance to change in motion (inertia) manifests itself. An object with greater mass will have a larger inertia and will therefore require a greater force to produce the same acceleration.
Moment of Inertia: This concept applies to rotational motion and describes the resistance of an object to changes in its angular velocity. It depends on the mass distribution of the object and its axis of rotation. The formula for moment of inertia varies depending on the shape of the object, but generally involves summing the product of each particle's mass and the square of its distance from the axis of rotation.
So, while the Law of Inertia itself doesn't have a specific formula, understanding the related concepts of Newton's Second Law and Moment of Inertia can help you analyze situations involving objects and their resistance to changes in motion.
12) Photosynthesis is a chemical reaction where carbon dioxide and water react to form glucose (C6H12O6) and oxygen gas. Which represents the proper balanced equations for photosynthesis?
Answer : The balanced chemical reaction will be,
[tex]6CO_2+6H_2O\overset{sunlight}\rightarrow C_6H_{12}O_6+6O_2[/tex]
Explanation :
Photosynthesis : It is a type of chemical process which occurs in the green plants or the living organisms.
During the photosynthesis process, carbon dioxide reacts with the water in the presence of sunlight to gives product as glucose and oxygen.
In this reaction, carbon dioxide and water molecule are the reactants and glucose and oxygen are the products.
The balanced chemical reaction will be,
[tex]6CO_2+6H_2O\overset{sunlight}\rightarrow C_6H_{12}O_6+6O_2[/tex]
the highest pitched sound that a human ear can detect is about 21 kHz. on the other hand dolphins can hear ultrasound with frequencies up to 280 kHz. what is the speed of sound in water if the wavelength of ultrasound with a frequency of 2.80 x 10^5 Hz is 0.510 cm?
Final answer:
The speed of sound in water is approximately 1428 m/s, calculated using the equation v = f × λ with the given frequency of ultrasound at 280 kHz and a wavelength of 0.510 cm.
Explanation:
The question asks about the speed of sound in water given the frequency and wavelength of ultrasound. In physics, the relationship between speed (v), frequency (f), and wavelength (λ) is given by the equation v = f × λ. With a frequency of 2.80 × 105 Hz (280 kHz) for dolphins and a wavelength of 0.510 cm or 0.00510 m, the speed of sound in water can be calculated as follows: v = 2.80 × 105 Hz × 0.00510 m, which gives v = 1428 m/s, the approximate speed of sound in water.
whats the difference between work and power
As concentration increases by a tenth,what happens to the pH?
As concentration of a solution, increases by a tenth, the pH will become basic. The pH scale measures how acidic or basic the substance is, where 0 is the most acidic due to increase in H+ in a concentration, 14 is the most basic because of low H+ concentration and 7 is considered neutral with equal number of H+ and OH- ions.
Environment includes _______.
A friends and clothing
B family and clothing
C clothing and movies
D friends and family
in a human cannonball a person is shot from a cannon with a barrel that is 3.05 m long. 16700 J of work are done to accelerate the acrobat out of the cannon. what is the force exerted on the acrobat
A race car starting from rest accelerates uniformly at a rate of 4.90 meters per squared. What is the cars speed after it has traveled 200 meters?
The race car's speed after it has traveled 200 meters, starting from rest and accelerating uniformly at a rate of 4.90 m/s², is approximately 44.27 meters per second.
Explanation:Given that the race car starts from rest and accelerates uniformly, we can apply the known physics equation for motion: v² = u² + 2as, where 'v' is the final velocity, 'u' is the initial velocity, 'a' is the acceleration, and 's' is the distance covered.
In this case, the car starts from rest, so 'u' is 0. The acceleration 'a' is given as 4.90 m/s², and the distance travelled 's' is 200 meters. Substituting these values into the equation, we get: v² = 0 + 2 * 4.90 * 200. Solving this, we find that 'v²' equals 1960, and therefore 'v' (the speed of the car) would be the square root of 1960, which is approximately 44.27 meters per second.
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How much work can a 23,000 Watt car engine do in 35 seconds if it is 100% efficient?
Answer:
Work done, W = 8,05,000 J
Explanation:
It is given that,
Power of car engine, P = 23,000 watt
Time taken, t = 35 s
The work done per unit time is called the power of the car engine.
[tex]P=\dfrac{W}{t}[/tex]
[tex]W=P.t[/tex]
[tex]W=23000\times 35[/tex]
W = 8,05,000 J
Hence, this is the required solution
Physics Help Please!!! All multiple choice!
1.) Does an object moving in uniform circular motion have constant centripetal acceleration?
True or False
2.) How do the angular velocities of three knots on a rope compare as it is swung around in a circle? How about their speeds?
a.) the angular velocity and linear velocities are the same
b.) the linear velocities are the same, the angular velocity increases as you move toward the outside dot
c.) the angular velocity is the same, the linear velocities are fastest in the center
d.) the angular velocity is the same, the linear velocities are fastest on the outside
e.) both the linear and angular velocities increase as you move out
3.) An object travels with a constant speed in a circular path. The net force on the object is
a.) zero
b.) toward the center
c.) away from the center
d.) tangent to the object's path
Wave energy can only be transmitted through a material medium. wave energy can only be transmitted through a material medium.
a. True
b. False
It's False that wave energy can only be transmitted through a material medium. While sound waves need a material medium to travel, electromagnetic waves like light or radio waves can travel even in a vacuum.
Explanation:The statement 'wave energy can only be transmitted through a material medium' is False. Although some waves, such as sound waves, require a material medium (like air, water, or a solid substance) to travel, others do not. Specifically, electromagnetic waves, including radio waves, light waves, and X-rays, can travel in a vacuum, i.e., space where there is no material medium present.
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which part of a circuit creates an electric force field that makes it possible for the circuit to work
which type of weathering creates karst topography
Karst topography is created by the chemical weathering process of carbonation
Many people believe that the atomic number of the atom is the number of electrons in the atom. Describe when this is the case
Answer: The atomic number of the atom is the number of electrons in the atom only when the atom is neutral.
Explanation: For a neutral atom, the number of positive charges is equal to the number of negative charges and thus the atomic number is equal to the number of electrons or the number of protons.
But for a positive and a negative ion, the electrons are lost and gained respectively by that element and thus the number of electrons are not equal to the number of protons. Now atomic number is equal to the number of protons only. The number of electrons = number of protons - charge.
Example: For sodium [tex]Na[/tex] , the atomic number is 11 and it has 11 electrons.
For sodium ion [tex]Na^+[/tex] , the atomic number is 11 but the number of electrons = (11-1) = 10.
A 98-kg fullback is running along at 8.6 m / s when a 76-kg defensive back running in the same direction at 9.8 m / s jumps on his back. What is the post-collision speed of the two players immediately after the tackle
The question requires calculating the post-collision speed of two football players using the law of conservation of momentum. The initial momenta of the players are summed up and then divided by their combined mass to find the final velocity after collision, using the formula: initial momentum = (combined mass) * final velocity.
Explanation:The subject of this question involves applying the conservation of momentum to find the post-collision speed of two football players. To solve the problem, we use the principle that in an isolated system (without external forces), the total momentum before the collision is equal to the total momentum after the collision. The formula for momentum is p = mv, where m is the mass and v is the velocity. For two objects colliding and moving together:
Given:
- Mass of fullback, m1 = 98 kg
- Velocity of fullback, v1 = 8.6 m/s
- Mass of defensive back, m2 = 76 kg
- Velocity of defensive back, v2 = 9.8 m/s
We calculate the total initial momentum:
initial momentum = (m1 * v1) + (m2 * v2)
Now, because after the collision they move together as one object, their combined mass is (m1 + m2), and let's call their final velocity vf. The conservation of momentum tells us that:
initial momentum = (m1 + m2) * vf
Therefore, we can solve for vf as follows:
vf = initial momentum / (m1 + m2)
By plugging in the given values, we can compute the post-collision speed of the two players immediately after the tackle.
Describe the shape of a convex lens and explain what it does to light.
A person having a mass of 85 kg sits on the edge of a horizontal rotating platform, 2.2 m from the center of the platform, and has a tangential speed of 6.6 m/s. calculate the angular momentum of the person
The angular momentum of a person with a mass of 85 kg sitting on the edge of a rotating platform with a tangential speed of 6.6 m/s and a distance of 2.2 m from the center is 1233 kg·m²/s.
Explanation:The student asked how to calculate the angular momentum of a person sitting on the edge of a rotating platform. To find the angular momentum (L), we can use the formula L = mvr, where m is the mass of the person, v is the tangential velocity, and r is the distance from the center of rotation to the point where the person is sitting.
In this case, the mass (m) is 85 kg, the tangential speed (v) is 6.6 m/s, and the radius (r) is 2.2 m. Hence, the angular momentum is:
L = 85 kg × 6.6 m/s × 2.2 m = 1233 kg·m²/s
A TV with a power rating of 400 W uses 0.6 kWh in one day. For how many hours was the TV on during this day? Round answer to the tenths and include the unit.
Final answer:
The TV with a power rating of 400 W, which used 0.6 kWh of energy in one day, was on for 1.5 hours.
Explanation:
The question is asking us to find the number of hours a TV with a power rating of 400 W was on if it used 0.6 kWh in one day. To answer this, we will use the formula for energy consumption:
E = P × t
where E is energy in kilowatt-hours, P is power in kilowatts, and t is time in hours. Since 1 W = 0.001 kW, we first convert the TV's power to kilowatts:
P = 400 W × 0.001 kW/W = 0.4 kW
Now we rearrange the formula to solve for t:
t = E / P
t = 0.6 kWh / 0.4 kW = 1.5 hours
Therefore, the TV was on for 1.5 hours that day.
1. A 2.00 kg cart on a frictionless track is pulled by force of 3.00N. What is the acceleration of the cart?
what would happen if organ systems failed to wok together
Answer:
This
Explanation:
Our body shape, production of red blood cells, and the protection of major organs in the body are all in the performance of the skeletal system. If this system fails, organs throughout the body will fail as well, red blood cells will not be able to be produced, and movement will be impossible
Our solar system is located very close to the center of the Milky Way galaxy, outside of the spiraling arms.
True
False
The correct answer is
False.
In fact, our solar system is located very far from the centre of the Milky Way Galaxy. In particular, it is located in the Orion Arm, about 26 000 light-years from the centre of the galaxy.
Answer: false it is a spiral
Explanation:
Which of the following make up the three regions of the brain?
A.
anteriorbrain, midbrain, and innerbrain
B.
forebrain, midbrain, and hindbrain
C.
forebrain, middlebrain, and innerbrain
D.
anteriorbrain, betweenbrain, and posteriorbrain
Answer: B. forebrain, midbrain, and hindbrain
The human brain is a complex organ that acts as a control center of a body. Being a component of central nervous system, the brain sends, receives, processes and directs sensory information. There are three regions present in the brain, and each region exhibit specific functions. The three regions named as forebrain, midbrain and hindbrain.
The forebrain: It functions as thinking part of the brain. It processes the sensory information that are collected from various sense organs such as eyes, ears, nose, skin and tongue.
The midbrain: It connects the forebrain and the hindbrain. It functions as a bridge between forebrain and hindbrain, serves to transfer signals from hindbrain and forebrain. It deals with the motor control, hearing, vision, temperature regulation, and alertness.
The hindbrain: It controls the heart rate, blood pressure, sleep and waking functions and breathing.
Question 1
Which of the following is a nontimber forest product?
Question options:
lumber
turpentine
paper
charcoal
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Question 2
When areas were deforested during the early Renaissance, what was the response?
Question options:
Plant new trees.
Use fires to clear underbrush and dead wood.
Move on to another forested area.
Apply selective tree harvesting to prevent further damage.
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Question 3
How can timber be renewed?
Question options:
starting a tree plantation
clear-cutting forest areas
starting a controlled fire
pruning old trees
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Question 4
Which is the most common method of tree harvesting for an even-aged forest stand?
Question options:
selective cutting of single trees
selective cutting of groups of trees
shelterwood cutting
clear-cutting
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Question 5
Which of the following fire-management methods reduces outbreaks of pests and diseases?
Question options:
suppressing a fire at early stages
preventing fires
controlled burning
suppressing a fire altogether
Forest products are defined as forest litter, fruits, resins, and forest trees. The non-timber forest products include products that are not derived from the woods. These have negative effects on the forest ecosystem, as they are used by people to meet the requirements of the community.
The correct answers are:
1. Turpentine
2. Move on to another forested area
3. Starting a tree plantation
4. Clear-cutting
5. Controlled burning
The non-timber forest products or NTFP are:
1. Turpentine is an antiparasitic substance, which is used to treat diseases like myiasis. It is obtained from the distillation of resins of trees like pines. It is not obtained from timber. Lumber, paper, and charcoal are all forest products.
2. Deforestation is the large-scale elimination of trees and plants. In the renaissance period, the demand for agricultural lands, colonization, and timber caused the increased removal of trees. The people in the renaissance period shifted to another forest area to meet the requirements of the community.
3. Timber is one of the sustainable and most used forest products. It is the ultimate renewable product and can be renewed by starting a tree plantation. Reforestation is one of the most effective ways to renew forest products.
4. Clear-cutting is the method of harvesting and regenerating forests. It involves clearing of trees from a forest site, and re-plantation of a new, even-age stand of timber is performed. Thus, a tree harvesting method for even-aged forest stand is clear-cutting.
5. Controlled-burning or prescribed burning is the method of burning forests to improve their health. The burns are scheduled for a given period of time and are not a threat to people and communities nearby. It is also done to reduce the outbreaks of pests and diseases. The high temperature eliminates the organisms and improves the health of the forest.
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When the energy of a stimulus falls below the absolute threshold, its presence cannot be detected. true or false?
What is the the acceleration of a proton that is 4.0 cm from the center of the bead? input positive value if the acceleration is directed toward the bead and negative if it is directed away from the bead?