Question

Which of the following chemical reactions is an oxidation-reduction reaction?

Answer
WO3 + 3H2 W + 3H2O
KNO3 + LiCl LiNO3 + KCl
CaSO4 + 2NaCl Na2SO4 + CaCl2
Mg(NO3)2 + 2HBr MgBr2 + 2HNO3
According to the collision theory and model created to explain the collision theory, what is the best explanation for why a higher concentration makes a reaction go faster?
There are more collisions per minute.
It increases the distance between the particles.
It increases the average kinetic energy of the particles.
It increases the average kinetic energy and there are more collision per minute.

Answer 1

Answer: 1. Option A and 2. Option D

In Redox reaction (oxidation-reduction) there should be change in oxidation no.

In A, oxidation no of W is changed from -6 to zero , Reduction (oxidation no Decreased) and oxidation no of Hydrogen is increased from zero to +1, oxidation (increase in oxidation no).

In remaining, there is no change in oxidation number.

2. Greater the concentration, more the collisions between the molecules and more the kinetic energy which reduce the activation energy and speed up the reaction.

Answer 2

1) Reactions which involves both a reduction process and a complementary oxidation process are called oxidation-reduction.they can't be double replacement reactions.
Hence,
WO3 + 3H2 ---> W + 3H2O is an oxidation-reduction reaction