How many moles are there in 4.3X 10^24 atoms of He

If the atomic mass of an atom is 34 and the atom contains 13 protons, how many neutrons does the atom contain?

Why is the bond angle in a water molecule less than the bond angle of methane? a. the central oxygen atom in water has two lone pairs of electrons, whereas the central carbon atom in methane has no lone pairs. b. the central hydrogen atom in water has one lone pair of electrons, whereas the central carbon atom in methane has two lone pairs. c. the central oxygen atom in water has four lone pairs of electrons, whereas the central carbon atom in methane has only one lone pair. d. the central oxygen atom exerts more repulsive force on surrounding atoms than the central carbon atom in methane does. reset next

Δu of , in kj/kg, as it isto k, (a)as a of , (b) at , (c) at .