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3 years ago

Question 5

Chemistry

1 answer:

Stolb23 [73]3 years ago

8 0

Answer:

There are 17.64% students received B+ grades.

Explanation:

It is given that,

Total number of students in chemistry class is 17

We need to find the percentage received by B+.

Number of students having B+ grades are 3 (from graph)

Required percentage = $P=\dfrac{3}{17}\times 100=17.64\%$

So, there are 17.64% students received B+ grades.

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1. Which list of nuclear emissions is arranged in order from the least penetrating power to

Tpy6a [65]

Answer:

A) alpha particle, beta particle, gamma ray

Explanation:

Alpha beta and gamma radiations are the examples of ionizing radiations. When an atom is an excited state and having high energy, the atom is in unstable state. The excess of energy is released by the atom to get the stability. The released energy is in the form of radiations which may include alpha, beta, gamma, X-ray etc.

Properties of alpha radiation:

Alpha radiations can travel in a short distance.

These radiations can not penetrate into the skin or clothes.

These radiations can be harmful for the human if these are inhaled.

These radiations can be stopped by a piece of paper.

₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴ + energy

Beta radiations:

The mass of beta particle is smaller than the alpha particles.

They can travel in air in few meter distance.

These radiations can penetrate into the human skin.

The sheet of aluminum is used to block the beta radiation

⁴₆C → ¹⁴₇N + ⁰₋₁e

The beta radiations are emitted in this reaction. The one electron is ejected and neutron is converted into proton.

Gamma radiations:

Gamma radiations are high energy radiations having no mass.

These radiations are travel at the speed of light.

Gamma radiations can penetrate into the many materials.

These radiations are also used to treat the cancer.

Lead is used for the protection against gamma radiations because of its high molecular density.

The lead apron are used by the person when treated with gamma radiations.

Lead shields are also used in the wall, windows and doors of the room where gamma radiations are treated, in-order to protect the surroundings.

7 0

3 years ago

Which part of the experiment is not touched by the independent variable or is the normal/comparison

kobusy [5.1K]

The part of the experiment that’s is not touched by the independent variable and is for comparison is called the :
Control Group

8 0

3 years ago

Determining Density and Using Density to Determine Volume or Mass

Shalnov [3]

corrected question:

Determining Density and Using Density to Determine Volume or Mass

(a) Calculate the density of mercury if 1.00 × 10 g occupies a volume of 7.36 cm³

(b) Calculate the volume of 65.0 g of liquid methanol (wood alcohol) if its density is 0.791 g/mL.

(d) Calculate the density of a 374.5-g sample of copper if it has a volume of 41.8 cm³ A student needs 15.0 g of ethanol for an experiment. If the density of ethanol is 0.789 g/mL, how many milliliters of ethanol are needed? What is the mass, in grams, of 25.0 mL of mercury (density = 13.6 g/mL)?

Answer:

density = $\frac{mass}{volume}$

ρ=m/v ,m=ρv, v=m/ρ

(a)m=1*10g , v=7.36cm³

ρ=10/7.36 =1.36g/cm³

(b) m=65g, ρ=0.791 g/mL.

v= 65/0.791 =82.17g/mL

m=19..32*8=154.56g/cm³

(d) mass of copper=374.5g , v=41.8cm³

ρ=374.5/41.8 =8.96g/cm³

mass of ethanol=15g, density of ethanol=0.789g/mL

v=15/0.789 =19.01mL

volume of mecury=25mL, density of mercury=13.6g/mL

m=25*13.6=340g

4 0

3 years ago

If 38.5 grams of potassium react with excess oxygen gas, how many grams of potassium oxide can be produced? 4K + O2 yields 2K2O

Lera25 [3.4K]

Answer:

46.40 g.

Explanation:

It is a stichiometric problem.

The balanced equation of the reaction: 4K + O₂ → 2K₂O.

It is clear that 4.0 moles of K reacts with 1.0 mole of oxygen produces 2.0 moles of K₂O.

We should convert the mass of K (38.5 g) into moles using the relation:

<em>n = mass / molar mass,</em>

n = (38.5 g) / (39.098 g/mol) = 0.985 mole.

<em>Using cross multiplication:</em>

4.0 moles of K produces → 2.0 moles of K₂O, from the stichiometry.

0.985 mole of K produces → ??? moles of K₂O.

∴ The number of moles of K₂O produced = (0.985 mole) (2.0 mole) / (4.0 mole) = 0.4925 mole ≅ 0.5 mole.

Now, we can get the mass of K₂O:

∴ mass = n x molar mass = (0.5 mole) (94.2 g/mol) = 46.40 g.

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3 years ago

Let’s suppose I place a live mouse in closed chambers with a CO2 sensor. In Chamber A, the mouse was given caffeine; therefore t

adell [148]

Answer:

Explanation:

Chamber

6 0

3 years ago