Question

1.Which of the following is not true of polar covalent bonds?

A. Polar covalent bonds create two poles across the bond.
B. Polar covalent bonds result from the unequal sharing of electrons.
C. Electronegativity differences for atoms with polar covalent bonds range between 0.5 and 2.0.
D. Polar covalent bonds exist between atoms of the same element.

2. Which of the following would not increase the rate of most reactions?

A. Removing an inhibitor
B. Lowering the concentration of the reactants
C. Increasing the temperature
D. Adding a catalyst

Answer 1

Answer: For question 1, correct option is D.

For question 2, correct option is B.

Explanation:

For question 1: A polar covalent bond is the chemical bond where electrons are unequally shared between the two different elements having different electrongativities. 2 poles are generated in this bond.

According to Pauling's electronegativity rule, difference between the electronegativities of elements in a polar covalent bond is from 0.5 to 2.0

Hence, polar covalent bond can never exist between the atoms of the same element.

For Question 2:

Option 1: Inhibitor decreases the rate of the reaction, but we are removing the inhibitor, so the rate will be increased.

Option 2: For a reaction,

`aA+bB\rightarrow cC+dD`

`rate=k[A]^a[B]^b`

As rate is directly proportional to the reactants, so by lowering the concentration of the reactants, the rate will also decrease.

Option 3: By increasing the temperature, collisions also increases and this collision results in the formation of the product. Hence, increasing the rate of the reaction.

Option 4: Adding a catalyst increases the rate of the reaction by lowering down the activation energy of the reactants.