How does density change when the state of matter changes from solid to liquid?

Which additional product balances the reaction h2so4 + 2naoh → na2so4 + 2h2o 2oh h2o2 h3o

A15,000 kg rocket traveling at +230 m/s turns on its engines. over a 6.0 s period it burns 1,000 kg of fuel. an observer on the ground measures the velocity of the expelled gases to be −1,200 m/s.

Asmall electric heater, immersed in 80g of water in a calorimeter of 40j/k raises the temperature from 10.5 degree celsius to 25 degree celsius in 12 minutes. using the same apparatus with 50g of oil instead of water, it is found that the temperature of oil rises from 7 degree celsius to 27 degree celsius in 10 minutes. find specific heat capacity of the oil.