If a lone pair of electron is present in the central atom does that mean it is a polar molecule?

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

Ahelium balloon contains 16.9 l of helium at stp. how many atoms of helium are in the balloon

How many moles of potassium are needed to react completely with 12.8 moles of magnessium bromide?