2 boxes of A
Because C = A + B
2 of A = 20 grams
at the other hand we have 2 of B = 10
So 20 + 10 = 30 grams
The heat lost is 
The heat lost when the ice is cooled from 400k to 263K can be calculated using the formula of heat transfer.
<h3>Heat Transfer</h3>
This is the heat transferred from a body of higher temperature to a body of lower temperature.

- Q = Heat Transfer
- m = mass = 1277g
- ΔT = change in temperature

We converted the temperature from kelvin scale into Celsius scale and find the change in temperature.
Solving for heat transfer

The heat loss is approximately 
Learn more on heat transfer here;
brainly.com/question/16055406
The answer is the third choice because is oxidation half reactions, only the oxidation state of the reducing agent changes; in this third choice, Fe2+ is oxidized and becomes Fe3+. Just keep in mind that half reactions usually include the change in electrons:
Fe2+ -> Fe3+ +e-<span />
The symbol for Chromium is Cr
Answer:
Option (D)
Explanation:
Chlorofluorocarbon is referred to as one of the important greenhouse gas, that is responsible for the depletion of the ozone layer. It was earlier extensively used in the refrigerators, but are later observed that as the CFC molecules are disintegrated in the atmosphere, it gives rise to the elimination of chlorine atoms that destroy the ozone layer, allowing the ultraviolet radiations to enter the earth's atmosphere. So, the use of CFCs has been banned globally by international treaties.
This gas is long-lasting, and remains in the atmosphere for about 20 to 100 years, is not that effective to human bodies, and present in the stratosphere in a very small amount.
Thus, the correct answer is option (D).