Answer: 4Kcal
Explanation:
H= mcø
M=200g
C= 1 cal/g/°c
Ø= 40-20=20°c
H= 200*1*20= 4000calories= 4Kcal
The answer to this question would be: isotonic
An isotonic solution has a same tonicity/concentration to the cell. This kind of solution will not cause osmosis to occur so it wouldn't shrink or swell the cells. This is why an isotonic solution is safer for the cells. The normal saline solution is isotonic to human cells and used frequently in medicine to replace body fluid.
So half life is the time taken for a sample to decay to half its original mass, its a constant and applies to any original mass, it could be 5g or 1kg, it will take the same amount of time for the original mass to half. In this case the half life is 3 days.
After 3 days the sample will be at half its original mass, now 50g.
Now we can treat the 50g as if its a new sample. After another 3 days (6 days in total) there will be half of 50g left, = 25g.
Answer : The correct option is, (d) inversely proportional to volume and directly proportional to the kelvin temperature
Explanation :
Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

Charles' Law : It is defined as the volume of the gas is directly proportional to the temperature of the gas at constant pressure and number of moles.

Gay-Lussac's Law : It is defined as the pressure of the gas is directly proportional to the temperature of the gas at constant volume and number of moles.

Combined gas law : It is the combination of Boyle's law, Charles's law and Gay-Lussac's law.
The combined gas equation is,

or,

From the above information we conclude that the pressure exerted by a gas is inversely proportional to volume and directly proportional to the kelvin temperature.
Hence, the correct option is, (d)