a.

Activation energy is high

b.

A catalyst is required

c.

It occurs reversibly

d.

Heat energy is absorbed

a.

Natural gas

b.

Nuclear

c.

Wind

d.

Solar

a.

is hard and brittle

b.

is light and resists corrosion

c.

has high density and conducts electricity

d.

is malleable and ductile

a.

Linear

b.

Pyramidal

c.

Tetrahedral

d.

V-shaped