All categories

3 years ago

There are many important laws and theories in science. Which of the following is a law of science?

Chemistry

2 answers:

garri49 [273]3 years ago

7 0

Answer: Gravity will pull two objects toward each other

Explanation:

Ghella [55]3 years ago

7 0

Answer:C

Explanation:Gravity

You might be interested in

DNA has 2 strands. if the sequence of nucleotides of one strand was known, is it possible to use the information to determine th

ANTONII [103]

DNA has four main components.
Adenine=A
Cytosine=C
Guanine=G
Thymine=T

Since each letter has an opposite it would be possible by considering the pairs.
A:T
C:G

So, if one strand went as so:
AGCCTAGGTAC
The corresponding strand would be mirrored with the match: TCGGATCCTG

3 0

3 years ago

The higher an electromagnetic wave's frequency, the lower its

Arlecino [84]

Wavelength because it is shorter

6 0

3 years ago

an unknown volume of gas has a pressure of 0.50 atm and temperature of 325k. if the pressure is raised to 1.2atm and the tempera

postnew [5]

117 L. You can start by making a table to organize the information you are given. Then, you can use the formula PV/T=PV/T and plug in the numbers you have. You then solve for the missing volume. Remember that the initial pressure, temperature, and volume should be on one side of the equal sign, and the final pressure, volume, and temperature should be on the other side.

6 0

3 years ago

Blast furnaces extra pure iron from the Iron(IIl)oxide in iron ore in a two step sequence. In the first step, carbon and oxygen

OLga [1]

Answer:

5.9 kg

Explanation:

We must work backwards from the second step to work out the mass of oxygen.

1. Second step

Mᵣ: 55.84

Fe₂O₃ + 3CO ⟶ 2Fe + 3CO₂

m/kg: 7.0

(a) Moles of Fe

$\text{Moles of FeO} = \text{7000 g Fe} \times \dfrac{\text{1 mol Fe}}{\text{55.84 g Fe}} = \text{125 mol Fe}$

(b) Moles of CO

$\text{Moles of CO} = \text{125 mol Fe} \times \dfrac{\text{3 mol CO}}{\text{2 mol Fe}} = \text{188 mol CO}$

However, this is the theoretical yield.

The actual yield is 72. %.

We need more CO and Fe₂O₃ to get the theoretical yield of Fe.

(c) Percent yield

$\begin{array}{rcl}\text{Percent yield} &=& \dfrac{\text{ actual yield}}{\text{ theoretical yield}} \times 100 \, \%\\\\ 72. \, \% & = & \dfrac{\text{188 mol}}{\text{actual yield}} \times 100 \,\%\\\\0.72 &= &\dfrac{\text{188 mol}}{\text{actual yield}}\\\\\text{Actual yield} & = & \dfrac{\text{188 mol}}{0.72}\\& = & \textbf{261 mol}\\\\\end{array}$

We must use 261 mol of CO to get 7.0 kg of Fe.

2. First step

Mᵣ: 32.00

2C + O₂ ⟶ 2CO

n/mol: 261

(a) Moles of O₂

$\text{Moles of O}_{2} = \text{261 mol CO} \times \dfrac{\text{1 mol O}_{2}}{\text{2 mol CO}} = \text{131 mol O}_{2}$

(b) Mass of O₂

$\text{Mass of O}_{2}= \text{131 mol O }_{2} \times \dfrac{\text{32.00 g O}_{2}}{\text{1 mol O}_{2}} = \text{4180 g O}_{2}$

However, this is the theoretical yield.

The actual yield is 71. %.

We need more C and O₂ to get the theoretical yield of CO.

(c) Percent yield

$\begin{array}{rcl}71. \, \% & = & \dfrac{\text{188 mol}}{\text{actual yield}} \times 100 \,\%\\\\0.71 &= &\dfrac{\text{4180 g}}{\text{actual yield}}\\\\\text{Actual yield} & = & \dfrac{\text{4180 g}}{0.71}\\\\& = & \text{5900 g}\\& = & \textbf{5.9 kg}\\\end{array}$

We need 5.9 kg of O₂ to produce 7.0 kg of Fe.

6 0

4 years ago

What would be an example of a chemical change that took a long time to occur?

nydimaria [60]

<span>rusting takes a long time, and rusting is a chemical change.</span>

5 0

4 years ago