A group of science students collect bacterial swabs from several locations inside their school. The collected bacterial swabs are spread over an agar-filled petri dish and bacteria colonies are grown. The students then install hand sanitizer dispensers throughout the school. One month later the students collect bacterial swabs from the same locations around the school and bacteria colonies are grown. Bacterial growth is counted for each sample and the data is compared.

What might be the question the students are asking in this experiment?

A) How long does bacteria live
B) Why does bacteria grow at schools
C) Does my school have more bacteria than the average school?
D) Does the addition of hand sanitizer dispensers throughout the school reduce the amount of bacteria?

Answer:Hydrogen gas is prepared in laboratory by the action of dilute HCl upon granulated zinc. Note: This is a redox reaction since Zn is oxidized and H+ ions is reduced here. Procedure: ... Some crystals of copper sulphate are added to increase the rate of reaction.

Explanation:

Answer:

The specific heat of aluminium is 0.8792 J/g °C  or 0.21 Cal/g °C

Explanation:

Step 1 : Write formule of specific heat

Q=mcΔT

with Q = heat transfer (J)

with m = mass of the substance

with c = specific heat ⇒ depends on material and phase ( J/g °C)

with ΔT = Change in temperature

For this case :

Q = 1680 Calories = 7033.824 J ( 1 calorie = 4.1868 J)

m = 100.0g

c= has to be determined

ΔT = 100 - 20 = 80°C

Step 2:  Calculating specific heat

⇒ via the formule Q=mcΔT

7033.824 J = 100g * c * 80

7033.824 = 8000 *c

c = 7033.824 /8000

c = 0,879228 J/g °C

or 0.21 Cal / g°C

The specific heat of aluminium is 0.8792 J/g °C  or 0.21 Cal/g °C

Final answer:

The specific heat of a metal can be found using the formula Q = mcΔT, which is rearranged to c = Q / (mΔT) to solve for c. For the 100.0 g sample of aluminum that released 1680 calories when cooled from 100.0°C to 20.0°C, the specific heat is calculated to be 0.21 cal/g°C.

Explanation:

To find the specific heat of a metal, you can use the formula Q = mcΔT, where Q is the heat absorbed or released in calories, m is the mass in grams, c is the specific heat capacity in cal/g°C, and ΔT is the change in temperature in degrees Celsius (°C).

In this case, we are given that a 100.0 g sample of aluminum released 1680 calories when cooled from 100.0°C to 20.0°C. The change in temperature (ΔT) is 100.0°C - 20.0°C = 80.0°C.

We can rearrange the formula to solve for c:
c = Q / (mΔT). Plugging in the given values:

c = 1680 cal / (100.0 g × 80.0°C)

After doing the calculation:

c = 1680 cal / 8000 g°C

c = 0.21 cal/g°C

So the specific heat of the metal is 0.21 cal/g°C.

Answer:

17/15 x 2/11 = 34/165

Answer:

D) Titanium-22

Explanation:

Titanium is one of the transition metal elements. It is the 22nd element on the periodic table.

From the statement of the problem:

  A  is the mass number of the unknown atom which is 49. The mass number is the number of protons and neutrons in the nucleus of the atom.

   Z is the atomic number of the unknown atom which is 22. The atomic number is the number of protons in an atom. It is the same as the number of electrons for a neutral atom.

To identify the element, we simply use the atomic number because the periodic table of element is a function of the atomic number Therefore, the element with atomic number 22 on the periodic table is Titanium.

If the liquid and the gas are both the same substance, then the gas particles are moving faster than the liquid particles, and this statement is false.

If they're different substances ... like for example liquid iron and oxygen gas ... then it could go either way, depending on the substances.

The statement that liquid particles move faster than gas particles is generally false. At the same temperature, gas particles typically move faster than liquid particles due to the difference in kinetic energy and intermolecular forces.

The statement 'Liquid particles move faster than gas particles' is generally false. The speed of particles depends on their temperature, not their state. However, at the same temperature, gas particles typically move faster than liquid particles.

This is due to the fact that gas particles have more kinetic energy and less intermolecular forces restricting their movement compared to liquid particles. For instance, particles in steam (gas) would move faster than particles in water (liquid) at the same temperature.

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Answer:

A physical quantity which is described completely by its mangnitude only is called scalar quantity. lenght distance time and ares are example of scalar quantity

Explanation:

hope it helps

Answer:

Classification, or taxonomy, is a system of categorizing living things.

Explanation:

There are seven divisions in the system: (1) Kingdom; (2) Phylum or Division; (3) Class; (4) Order; (5) Family; (6) Genus; (7) Species. Kingdom is the broadest division.

Answer:

The molecular formula of X is given as [tex]C_7 H_6 O_3[/tex]

Explanation:

[tex]Moles $C O_{2}=\frac{\text { mass }}{\text { molar mass }}=\frac{13.39 \mathrm{g}}{44.01 \mathrm{g} \text { per mole }}=0.304 \mathrm{mol}$\\\\moles $\mathrm{C}=$ moles $\mathrm{CO}_{2}=0.304 \mathrm{mol}$[/tex]

[tex]mass $C=$ moles $\times$ molar mass $=0.304 \mathrm{mol} \times 12 \frac{g}{m o l}=3.65g$\\\\moles $\mathrm{H}_{2} \mathrm{O}=\frac{2.35 \mathrm{g}}{18.02 \mathrm{g} \text { permole }}=0.130 \mathrm{mol}$\\\\moles $\mathrm{H}=2 \times$ moles $\mathrm{H}_{2} \mathrm{O}=0.130 \times 2=0.260 \mathrm{mol}$\\\\Mass $\mathrm{H}=0.260 \mathrm{mol} \times 1.008 \frac{g}{\mathrm{mol}}=0.262 \mathrm{g}$[/tex]

mass O = Total mass of the compound - (mass of C + mass of H)

=6.0 g - ( 3.65 + 0.262 ) g

=2.09 g

[tex]moles $O=\frac{2.09 g}{16 g \text { per mole }}=0.131 \mathrm{mol}$[/tex]

Least moles is for O that is 0.131mol and dividing all by the least we get

[tex]$\begin{aligned} C &=\frac{0.304}{0.131}=2.3 \\\\ H &=\frac{0.260}{0.131}=2 \\\\ O &=\frac{0.131}{0.131}=1 \end{aligned}$[/tex]

Since 2.3 is a fraction it has to be converted to a whole number so we multiply all the answers by 3

[tex]\\$C 2.3 \times 3=7$\\\\$H 2 \times 3=6$\\\\$O 1 \times 3=3$[/tex]

So the empirical formula is [tex]C_7 H_6 O_3[/tex]

Empirical formula mass

[tex]=(7 \times 12) +(6\times1.008)+(3\times16)=138.048g[/tex]

[tex]$n=\frac{\text { molar mass }}{\text { empirical formula mass }}=\frac{138}{138.048}=1$[/tex]

Molecular formula =n × empirical formula

[tex]=1 \times C_7 H_6 O_3[/tex]

Compound X  = [tex]C_7 H_6 O_3[/tex]  is the Answer

To find the molecular formula of Compound X, we calculate the empirical formula using the moles of carbon dioxide and water produced. The empirical formula is CH2O. The molecular formula is (CH2O)5.

To find the molecular formula of Compound X, we need to determine the empirical formula first. From the given information, we can calculate the moles of carbon dioxide and water produced. The moles ratio of carbon to oxygen in carbon dioxide is 1:2, while the moles ratio of hydrogen to oxygen in water is 2:1. Using these ratios, we can find the moles of carbon, hydrogen, and oxygen in Compound X. The empirical formula of X is CH2O.

The molar mass of the empirical formula is 30 g/mol. To find the molecular formula, we divide the molecular molar mass of X by the molar mass of the empirical formula. Dividing 138 g/mol by 30 g/mol gives us approximately 4.6, which we can round to 5. This means the molecular formula of X is (CH2O)5.

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Answer: D. An acid-base conjugate pair that keeps the pH from changing

Explanation: the answer is D. An acid-base conjugate pair that keeps the pH from changing, because we have to keep in mind which is the scope of this solution, and the scope is maintain the pH despite the changes in the solutions or support any change when you add another solution to the buffer.

also we need to know that a Buffer achieve their resistance to the changes of the pH, because of the presence of an equilibrium between the acid HA and its conjugate base.

This equilibrium give the properties to this solution to support the changes.

Answer:

Physical.

Explanation:

A chemical property would more be its reaction to water vs acid

Final answer:

The bendability of construction paper is a physical property. Physical properties include characteristics that can be observed without changing the substance's chemical identity.

Explanation:

The ability of construction paper to bend is related to its physical properties. Physical properties can be observed or measured without changing the identity of the substance. In the case of construction paper, its flexibility is a physical property because it informs us about the paper's ability to bend or change shape without altering its chemical composition.

Among physical properties, we find characteristics such as color, density, and malleability, which also includes the paper's ability to bend. Materials like construction paper are designed to be flexible and are often used for activities that rely on bending and shaping without breaking.

Answer:

a rock containing a lot of iron

Explanation:

Iron ore is an ore of iron and this implies a rock that contains a substantial amount of iron.

An ore is a naturally occurring rock type that hosts a certain type of metal or solid that can be won at profit with some gangue minerals. Iron ore is one such type of substance from which significant amount of iron can be extracted for use by man. The remaining part quite not useful is the gangue.