If diamond has an index of refraction of 2.417, use the equation v = - and the speed of light constant (2.998 108 m/s)

HELP PLEASE I dont understand this (7th Grade science)

Maksim231197 [3]

For the second one it is physical

7 0

3 years ago

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Calculate the grams of so2 gas present at stp in a 5.9 l container.

nata0808 [166]

Answer: The mass of sulfur dioxide gas at STP for given amount is 16.8 g

Explanation:

At STP conditions:

22.4 L of volume is occupied by 1 mole of a gas.

So, 5.9 L of volume will be occupied by = $\frac{1mol}{22.4L}\times 5.9L=0.263mol$

Now, to calculate the mass of a substance, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Moles of sulfur dioxide gas = 0.263 mol

Molar mass of sulfur dioxide gas = 64 g/mol

Putting values in above equation, we get:

$0.263mol=\frac{\text{Mass of sulfur dioxide gas}}{64g/mol}\\\\\text{Mass of sulfur dioxide gas}=(0.263mol\times 64g/mol)=16.8g$

Hence, the mass of sulfur dioxide gas at STP for given amount is 16.8 g

7 0

3 years ago

According to your study unit, what's the payoff that keeps volunteers using their own time to help their communities?

klasskru [66]

C. It's so rewarding, people feel emotionally high and fulfilled when they're done.

In volunteering, your primary motivation is to extend your help or assistance and make other people happy. Seeing people happy because of what you are doing, it the ultimate reward of volunteering. Happiness gained from this experience is priceless. It is worth more than any freebies or any material gains you will receive.

8 0

3 years ago

Which of the following reactions have a positive ΔSrxn? Check all that apply.

PolarNik [594]

Answer:

The reactions that have a positive ΔS rxn are the first and the fourth choices:

2A(g) + B(s) → 3C(g)

2A(g) + 2B(g) → 5C(g)

Explanation:

ΔS rxn is the change of entropy of the chemical reaction.

ΔS rxn = S after reaction - S before reaction.

Therefore, a positive ΔS rxn means that the entropy after the reaction is greater than the entropy before the reaction.

You may use some assumptions to predict whether a reaction will lead an increase or decrease of the entropy.

First, assume that all the non-shown conditions, such as temperature and pressure, are constant.

Under that assumption, and from the meaning of entropy as a measure of the disorder or randomness of a system you can predict the sign of the change of entropy.

2A(g) + B(s) → 3C(g)

1) The solid compounds, B(s) in this case, are very ordered and so they have low entropy.

2) Gas molecules are highly disordered (scattered), and the greater the number of molecules of the gas the larger the entropy, S).

Hence, since the product side shows 3 gas molecules and the reactant side shows 2 gas molecules and 1 solid molecule, you predict that the products have a larger entropy than the reactants, meaning an increase in entropy: ΔS rxn is positive.

2A(g) + B(g) → C(g)

Using the same reasoning, 3 gas molecules in the reactant side have more entropy than 1 molecule in the product side, and so the reaction leads to a decrease in the entropy: ΔS rxn is negative

A(g) + B(g) → C(g)

Again, 2 gas molecules in the reactant side have more entropy than 1 molecule in the product side, and so the reaction leads to a decrease in the entropy: ΔS rxn is negative

2A(g) + 2B(g) → 5C(g)

With the same reasoing, 5 molecules in the product side, lets you predict that will have more entropy than 4 molecules in the reactant side, and, the entropy will increase: ΔS rxn is positive.

6 0

4 years ago

Which of the following acids is in household vinegar? A nitric acid hydrochloric acid C fluoric acid D acetic acid

Free_Kalibri [48]

Answer: Out of the given options acetic acid is in household vinegar.

Explanation:

Household vinegar is the one that is commonly used in our home while cooking a number of dishes.

The common name of vinegar is acetic acid and its chemical formula is $CH_{3}COOH$ .

For example, vinegar (acetic acid) is used while making noodles.

Thus, we can conclude that out of the given options acetic acid is in household vinegar.

7 0

3 years ago