EmSAT Chemistry 3

Question 1

Which type of bonding is present in sodium chloride (NaCl)?

Accepted Answer

Ionic bonding

Answer

NaCl is formed by the transfer of an electron from sodium to chlorine, creating an ionic bond between Na⁺ and Cl⁻ ions.

Question 2

What is the oxidation state of sulfur in H₂SO₄?

Accepted Answer

+6

Answer

In H₂SO₄, hydrogen is +1 (×2 = +2) and oxygen is -2 (×4 = -8), so sulfur must be +6 to give an overall charge of zero.

Question 3

A reaction has a negative ΔH and a negative ΔS. Under which condition is the reaction spontaneous?

Accepted Answer

At low temperatures only

Answer

When ΔH < 0 and ΔS < 0, ΔG = ΔH – TΔS is negative (spontaneous) only at low temperatures where the enthalpy term dominates.

Question 4

Which of the following is an example of a nucleophilic substitution reaction?

Accepted Answer

Reaction of bromoethane with KOH(aq)

Answer

OH⁻ acts as a nucleophile attacking the carbon bonded to Br in bromoethane, replacing Br in an SN2-type substitution.

Question 5

What does Le Chatelier's principle predict when pressure is increased on the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g)?

Accepted Answer

Equilibrium shifts right, producing more NH₃

Answer

Increasing pressure shifts equilibrium toward the side with fewer moles of gas; the right side has 2 moles vs. 4 on the left, so more NH₃ is produced.

EmSAT Practice Test

EmSAT Practice Test

EmSAT Chemistry 3