Jeannie dropped a solid object into a beaker of water and observed it for five minutes. Based on her observations, she determined that only a physical change occurred.

Which of the following observations would indicate that only a physical change occurred after she added the object?
A.
The object broke apart and seemed to disappear when dropped into the glass of water.
B.
The object sank to the bottom when dropped into the glass of water.
C.
Bubbles formed around the object as it sank to the bottom of the water and did not resurface.
D.
The object floated on the top of the water when when dropped into the glass.

The term used to denote randomness is entropy, the correct option is C.

The entropy of an object is a measure of the amount of energy that cannot be used to perform work.

Entropy is also a measure of the number of possible configurations for atoms in a system. Entropy is a measure of uncertainty or randomness in this sense.

The entropy of a physical system is proportional to the amount of energy that is no longer available to do physical work in classical physics.

Entropy is central to the second law of thermodynamics, which states that any activity in an isolated system increases entropy.

Entropy cannot be destroyed by any means at any scale, so it cannot decrease overall.

Thus, the correct option is C.

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Answer:

the answer is 5⁷

Explanation:

it is 5 to the power of 7 because 5 is it base and then the 4 and 5 get added to get ur exponent

Final answer:

The density of an object with a mass of 15 grams and a volume of 3 cm³ is 5 grams per cubic centimeter (5 g/cm³).

Explanation:

The density of an object is calculated by dividing its mass by its volume. In this case, the mass of the object is given as 15 grams and the volume is 3 cm³. The formula for calculating density is:

Density = Mass / Volume

Applying the values provided:

Density = 15 g / 3 cm³ = 5 g/cm³

Therefore, the density of the object is 5 grams per cubic centimeter (5 g/cm³).

Rubidium's atomic number is 37.

Hope this helps!

Answer:

Atomic number 37!

Explanation:

Answer:

Intrusive, or plutonic, igneous rocks form when magma cools slowly below the Earth's surface. Most intrusive rocks have large, well-formed crystals. Examples include granite, gabbro, diorite and dunite.

Answer:

Intrusive, or plutonic, igneous rocks form when magma cools slowly below the Earth's surface. Most intrusive rocks have large, well-formed crystals. Examples include granite, gabbra, diorite and danite.

sorry if i spelled things wrong

Answer:

8.69 g

Explanation:

density = 1.1 g/mL

it means,

1 ml of the solution has a mass of 1.1 g

∴7.9 ml of the solution has a mass of =(1.1 x7.9) g

                                                              =8.69 g

Answer:

C. Oxidation occurs at the anode and reduction occurs at the cathode.

Choice number third is the correct option for the given question

Explanation:

Copper and silver nitrate are the two components that form a voltaic cell. These are the two main ingredients which make the Redox reaction possible. The dog reaction that is taking place result in development of charge.

Since copper here is the anode in the reaction oxidation happens here by the solution[tex]AgNO_3[/tex] is cathode this is where reduction takes place.

Answer:

783

Explanation:

Because all of the numbers are Sig figs but the first three of them are 783

To round 7834.87 to 3 significant figures, identify the first three non-zero numbers which are 7, 8, and 3. The next digit is '4', which is less than 5, so we don't round up. Therefore, when rounded to 3 significant figures, 7834.87 becomes 7830.

In the number 7834.87, rounding to three significant figures means we only keep the three most meaningful digits, typically the first three non-zero digits from the left side of the number. In this case, those numbers are 7, 8, and 3. When you round 7834.87 to the nearest three significant figures, look at the digit following the third significant figure. If that digit is 5 or higher, we round up the third significant figure. If it's 4 or lower, we leave the third significant figure as it is. In this case, the digit following the third significant figure is '4', which is lower than 5. So, 7834.87 rounded to three significant figures is 7830.

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Answer:

H3PO4 + 3RbOH > 3H20 + Rb3PO4

Explanation:

The chemical equation H3PO4 + RbOH → H2O + Rb3PO4 is correctly balanced as H3PO4 + 3RbOH → 3H2O + Rb3PO4, based on the principle of conservation of atoms.

The subject here is balancing chemical equations which is a core topic in high school chemistry. Balancing chemical equations involves adjusting the coefficients of the reactants and products to ensure that the number of atoms of each element is equal on both sides of the equation.

In the given equation H3PO4 + RbOH → H2O + Rb3PO4, the correct set of coefficients that balance the equation are H3PO4 + 3RbOH → 3H2O + Rb3PO4. So, for every one molecule of phosphoric acid (H3PO4), three molecules of Rubidium hydroxide (RbOH) react to form three molecules of water (H2O) and one molecule of Rubidium phosphate (Rb3PO4).

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“Ability to form a compound” is a chemical property.

Answer: Option A

Explanation:

Each element exhibits its characteristic physical and chemical properties. The physical properties of an element describes the boiling point, melting point, freezing point, density, inherent state of matter, electrical and thermal conductivity, etc. The change in physical properties occur when there is a change in the phases and not any change in the chemical composition.

But for chemical properties, these properties explain the bond strength of the elements. It helps to decide the reactivity, flammability of substances. The chemical properties of substance or element decide how easily it can react or get burned.

Any properties or reactions which lead to formation of compounds different from the reactants are considered as chemical change of the reactants. So we can say that the ability to form a compound is a chemical property as in this case, the reactants will react with each other in presence of external heat if required to form the product compound whose chemical composition and properties will be different from the reactants.

Answer:

" atomic radius is the measure of size of an atom from its center to its boundary of outer most shell "

Explanation:

Atomic radius is the distance from the center of nucleus to the point where the electronic density is maximum.

Types of Atomic Radii  :

Atomic radii are divided into three types:

1= Metallic radius

2= Covalent radius

3= Vander Waals radius.

Metallic radius:

Metallic radius is the half of the inter nuclear distance of two adjacent ions in metallic lattice. The valance electrons are free to move in metallic lattice therefore they are weakly attracted by ions of metals.

The metallic radius is always greater than covalent radius because in in covalent bond electrons are strongly attracted between the nuclei of atoms fro example, the covalents radius of Na2 and potassium is 154 and 203 pm respectively while the metallic radius is 186 and 231 pm respectively.

Covalent Radius:

It is the one half distance between the two covalently bonded nuclei of atoms of same element in a molecule.  

Van der Waals Radius:

It is one half distance between two adjacent atoms belonging to the two neighbor molecules of element in solid state. Its magnitude is depend upon the packing of atoms in the solid state.

For example Van der Waals radius of chlorine atom is 180 pm.

Periodic trend of atomic radius:

In period:

The Van der Waals and covalent radii decreases in the period from left to right with increase of atomic number. All alkali metals in the left of periodic table have largest size.

In Group:

The atomic radii increases from top to bottom with increase of atomic number.

Final answer:

The atomic radius is defined as half the distance between the nuclei of two identical atoms in a bond; commonly cited types include Van der Waals, ionic, and covalent radii.

Explanation:

Chemists define the atomic radius of an element as the mean or typical distance from the center of the nucleus to the boundary of the surrounding electron cloud. This boundary is not well-defined as electrons exist in probability density functions, making the exact edge of the atom difficult to pinpoint. The commonly used definitions include the Van der Waals radius, the ionic radius, and the covalent radius.

The covalent radius, often used in a practical sense, is half the distance between the nuclei of two identical atoms bonded covalently. The internuclear distance within molecules, which can be measured accurately, helps in determining these radii. For example, the covalent radius of chlorine is taken to be half the distance between two chlorine nuclei in a diatomic Cl2 molecule, which amounts to 99 pm.

Answer:

Explanation:

Tools, instruments, apparatus are very key to research works carried out in the laboratory. The more sophisticated they become, the more efficiency they provide in making ground breaking researches.

Over the years, technological advancement has afforded scientists with new way of achieving precision and accuracy in their procedures by developing cutting edge facitlities. These equipment can help carry out better experiment  and make observations simple and easy to do.

Explanation:

laboratory tools improve the observations made by a scientist in the following ways:

Answer:

1. 1 mi; 2. 0.5 kg; 3. 3.5 qt; 4. 0.0045 in

Explanation:

We must make the units of each measurement the same.

1. Kilometres vs. miles

[tex]d =\text{1 km} \times \dfrac{\text{1 mi}}{\text{1.609 km}} = \text{0.6 mi}[/tex]

The larger measurement is 1 mi.

2. Kilograms vs. pounds

[tex]m = \text{0.5 kg} \times \dfrac{\text{2.205 lb }}{\text{1 kg}} = \text{1.1 lb}[/tex]

The larger measurement is 0.5 kg.

3. Quarts vs. litres

[tex]V = \text{2.5 qt} \times \dfrac{\text{1 L }}{\text{1.057 qt}} = \text{2.3 L}[/tex]

The larger measurement is 2.5 qt.

4. Centimetres vs. inches

[tex]d = \text{0.0045 cm} \times \dfrac{\text{1 in }}{\text{2.54 cm}} = \text{0.0018 in}[/tex]

The larger measurement is 0.0045 in.

Answer: 1) 1.0mi 2) .5kg. 3) 2.5L 4). 0.0045in.

Explanation:

Answer:true

Explanation:

Answer:

The pH is 11

Explanation:

Because pH + pOH = 14

and pOH = - log [OH⁻] = - log (1 x 10⁻³) = 3

we can now calculate pH by manipulating equation one above

pH = 14 - pOH = 14 - 3 = 11

Thus the pH of the solution is 11

Answer:

a) 2 significant figures

b) 5 significant figures

c) 5 significant figures

d) 1 significant figures

Explanation:

• All non-zero digits are significant.

E.g. - 421 has 3 significant figures.

• Zeros between non-zero digits are significant.

E.g. - 502 has 3 significant figures.

• In a decimal less than 1, all zeros to the left of non-zero digits are not significant.

E.g. - 0.0345 has 3 significant figures.

Find the total number of hours needed by dividing the total amount earned by the amount per hour:

160 / 4 = 40 hours

Divide the total number of hours by hours for 1 day:

40  / 8 = 5

It will take 5 days.

3 days

Explanation:

4 dollars a hour

8 hours a day

total 160

4*24=160

24÷8=3

[3]

Answer:

1.5 x 10²²atoms

Explanation:

Given parameters:

Mass of Br = 1.98g

Unknown:

Number of atoms

Solution:

A mole of a substance is the amount of substance contained in the avogadro's number of particles.

To solve this problem, we must first find the number of moles present in the given mass of the Br atom:

       Number of moles = [tex]\frac{mass}{molar mass}[/tex] =  [tex]\frac{1.98}{80}[/tex]  = 0.025mole.

Now we know that:

       1 mole = 6.02 x 10²³

      0.025 mole = 0.025 x 6.02 x 10²³ = 1.5 x 10²²atoms

Given 1.98 g of bromine, using its atomic weight (79.9 g/mol) and Avogadro's number (6.022 × 10^23 atoms/mol), we calculate that there are approximately [tex]1.49 * 10^2^2[/tex] bromine atoms.

To determine the number of bromine atoms in a given mass of bromine, we will need to use the atomic weight of bromine, which is 79.9 g/mol, and Avogadro's number, which stipulates that there are [tex]6.022 * 10^2^3[/tex] atoms in a mole.

To convert the mass of bromine to moles, we will divide by the atomic weight: 1.98 g / 79.9 g/mol = 0.0248 moles.

To convert moles to atoms, we then multiply by Avogadro's number: 0.0248 moles × 6.022 × 10^23 atoms/mol = [tex]1.49 * 10^2^2[/tex]atoms.

So, there are approximately 1.49 × 10^22 atoms of bromine in 1.98 g of bromine.

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Is this supposed to be a question or something??? if so i need context.

Wood burning, particularly for home heating, involves the combustion of wood to release thermal energy. Modern techniques, such as the use of efficient wood stoves, aim to reduce the environmental impact by cutting down on pollutants. The sustainability of wood as a fuel largely depends on the sourcing and management of the harvested wood.

The process of wood burning in fireplaces or for home heating is an application of combustion, wherein wood is used as a biomass fuel. This process converts the carbon in wood into carbon dioxide and releases a significant amount of thermal energy. Modern home heating methods, such as high-efficiency wood stoves or fireplace inserts, have been developed to burn wood more efficiently than traditional open fireplaces. These advanced heating systems are designed to minimize pollutant emissions, such as carbon monoxide and particulate matter, making them a cleaner alternative to fossil fuels.

However, the sustainability of using wood as a fuel depends heavily on the source of the wood. If harvested from managed forests or urban trees that necessarily need to be removed, it can be a renewable resource. But, the indiscriminate cutting of wood, particularly in undeveloped countries for cooking and heating, can lead to deforestation and negatively impact ecosystems.

Answer: Hill is a Major characteristic used to differentinate between a plain and plateau

Explanation:

Answer:

A solid has a definite volume and adefinite shape.  

A liquid has a definite volume and no definite shape.  

A gas has no definite volume and no definite shape.

Explanation:

Solids

Solids have a definite volume and definite shape

The particles present in a solid are very closely packed since the intermolecular forces between them are very strong. The molecules do not move apart.

Liquids

Liquids have a definite volume and no definite shape

The particles present in a liquid are closely packed since the intermolecularforces holds the molecules close together. The molecules slide over each other.  Liquids take up  the shape of the container

Gases

Gases have no definite volume and no definite shape

The particles present in a gas are very loosely packed since the intermolecular forces are very weak.  There are no attractive forces between the molecules.  Gases spread through the container

Answer:

A solid has a definite volume and a definite shape.  

A liquid has a definite volume and no definite shape.  

A gas has no definite volume and no definite shape.

Explanation:

Answer:

Models

Explanation:

Models are abstractions of the real world. Models helps to mimick what is actually the true representation of a body. It is easier to work with models because they are our own creation. This makes them flexible to carryout any form of adjustments and manipulations. We can try out a model with different variables to simulate an obtainable result.

Models are easier to work with than the complex reality with a lot of factors and conditions that may not be easily predictable and under control.

Answer:

Hypothesis.

Explanation:

Investigation where only the independent variable is being tested by the scientist.

Answer:

Try a magic eraser!

Explanation:

Answer:

All you have to do is put a little rubbing alcohol on a rag or paper towel, rub it over the dried marks, and the Expo marker comes right off. It works on boards, books, and most other Expo marked surfaces (like refrigerators, windows, laminate countertops, etc).

Answer:

25.872 g of carbon dioxide will produced.

Explanation:

Given data:

mass of butane (C4H10) = 8.21 g

mass of carbon dioxide = ?

Solution:

Chemical equation

C4H10 + O2 → CO + H2O

Balanced chemical equation

2C4H10 + 13O2 → 8CO + 10H2O

First of all we will calculate the moles of butane.

number of moles = mass/ molar mass

number of moles = 8.21 g/ 58 g/mol

number of moles = 0.147 mol

from balanced chemical equation we will compare the moles of C4H10 with CO2,

             C4H10     :    CO2

                2           :      8

              0.147       :      8/2×0.147 = 0.588 moles

now we will calculate the mass of carbon dioxide from moles,

 mass of CO2 = number of moles × molar mass of CO2

 mass of CO2 =  0.588 mol × 44 g/mol

mass of CO2 = 25.872 g

By applying stoichiometry principles to the combustion of butane (C4H10), it is calculated that burning 8.21 grams of butane will produce approximately 24.82 grams of CO2.

The question asks to determine how many grams of CO2 are produced by burning 8.21 g of C4H10 (butane). To solve this, we first need to understand the balanced chemical equation for the combustion of butane, which is C4H10 + 13/2 O2 -> 4 CO2 + 5 H2O. This indicates that for every molecule of butane combusted, 4 molecules of CO2 are produced.

First, calculate the molar mass of butane (C4H10): (4x12.01) + (10x1.008) = 58.14 g/mol. Thus, 8.21 g of C4H10 is 8.21/58.14 = 0.141 moles. According to the balanced equation, combusting 1 mole of butane produces 4 moles of CO2, so 0.141 moles will produce 0.141 x 4 = 0.564 moles of CO2.

Finally, calculate the mass of CO2 produced: 0.564 moles x 44.01 g/mol (molar mass of CO2) = 24.82 grams of CO2.

Answer:

splitting of Barium atom

Explanation:

I just did the test :)

Answer:

Dependent variable

Answer: most is 3

Explanation:

Communicating Results