What do I have to do for both questions

What pressure will be exerted by 0.675 moles of a gas at 25*c if it is in a 0.750-l container?

Indicate whether the specified alkyl halides will form primarily substitution products, only elimination products, both substitution and elimination products, or no products when they react with sodium methoxide. 1-bromobutane 1-bromo-2-methylpropane 2-bromobutane 2-bromo-2-methylpropane

How many atoms are there in 5.70 mol of mg