An exothermic reaction is one that releases energy from the system to its surroundings, usually in the form of heat, but also in the form of light, electricity, or sound. Since the water gives off heat, the temperature of the water should be lower, so the answer might be B) The thermometer will show a decrease in temp.
The reaction for burning of charcoal or complete combustion is as follows:
From the above balanced reaction, 1 mole of carbon releases 1 mole of 
gas.
Converting mass of charcoal into moles as follows:
Molar mass of pure carbon is 12 g/mol thus,
The same moles of is released. Converting these moles into mass as follows:
m=n×M
Molar mass of is 44 g/mol thus,
Converting mass into kg,
Thus, total mass of gas released is 5.5 kg.
To solve this we use the
equation,
<span> M1V1 = M2V2</span>
<span> where M1 is the
concentration of the stock solution, V1 is the volume of the stock solution, M2
is the concentration of the new solution and V2 is its volume.</span>
<span>2.0 M x V1 = 0.50 M x 200 mL</span>
<span>V1 = 50 mL needed</span>
The partial pressure of hydrogen is 0.31 atm
calculation
find the number of hydrogen moles the container, that is
25/100 x 6.4 =1.6 moles of hydrogen
find the partial pressure for hydrogen in 1.6 moles
that is 6.4 moles= 1.24 atm
1.6 moles= ?
by cross multiplication
1.6moles x1.24 atm/ 6.4 moles= 0.31 atm
B. He was the first person to observe and identify living cells.
