Which of these would support the idea that mass is conserved in a reaction that produces a gas as a product? Group of answer choices

Subtracting the mass of the gas from the mass of the solid and liquid products.

Mixing the reactants and measuring their total mass.

Trapping the gas and measuring its mass.

Heating the reactants to ensure the reaction occurs in a gaseous state.

May someone me with these science questions

When 13.3 g koh is dissolved in 102.7 g of water in a coffee-cup calorimeter, the temperature rises from 21.4 °c to 31.53 °c. what is the enthalpy change per gram of koh (j/g) dissolved in the water? * take the density of water as 1.00 g/ml. * assume that the solution has a specific heat capacity of 4.18 j/g*k. enter to 1 decimal place. do not forget the appropriate sign /(+). canvas may auto-delete the (+) sign

A0.100-kilogram apple hangs in a tree 1.50 meter above the ground. ignore frictional effects, the total mechanical energy of the apples is