Is helium a gas, liquid or solid at room temperature

How many moles of no2 will form when 3.3 moles of cu are reacted with excess hno3?

What is the approximate mass of 25 cm3 of silver, if the density is 10.5 g/cm3? a. 0.42 g b. 2.4 g c. 42 g d. 260 g

4786 joules of heat are transferred to a 89.0 gramsample of an unknown material, with an initialtemperature of 23.0°c. what is the specific heat of thematerialif the final temperature is 89.5 °c?