Why do very few trees exist in a grassland ecosystem?

a.
not enough heat

b.
not enough topsoil

c.
not enough sunlight

d.
not enough precipitation

Hydrogenation reactions, in which h2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. in the simplest case, ethene (c2h4) and h2 form ethane (c2h6). if 140 kj is given off per mole of c2h4 reacting, how much heat (in mj) is released when 12 kg of c2h6 forms?