EmSAT EmSAT Chemistry 3

Question 1

What is the oxidation state of sulfur in H₂SO₄?

Accepted Answer

+6

Answer

In H₂SO₄: H is +1 (×2 = +2), O is −2 (×4 = −8). For the molecule to be neutral: +2 + S + (−8) = 0, so S = +6.

Question 2

What is a redox reaction?

Accepted Answer

A reaction where electrons are transferred between species

Answer

A redox (reduction-oxidation) reaction involves the transfer of electrons between chemical species. One species is oxidized (loses electrons) and another is reduced (gains electrons).

Question 3

Which element is reduced in: Zn + CuSO₄ → ZnSO₄ + Cu?

Accepted Answer

Copper

Answer

Cu²⁺ gains 2 electrons to become Cu (solid). Gaining electrons is reduction. Zinc is oxidized (loses electrons) to become Zn²⁺.

Question 4

What is the rate of a chemical reaction?

Accepted Answer

The change in concentration of reactants/products per unit time

Answer

Reaction rate is defined as the change in concentration of reactants or products per unit time. It tells us how quickly a reaction proceeds.

Question 5

Which factor does NOT affect reaction rate?

Accepted Answer

Color of the reactants

Answer

Reaction rate is affected by temperature, concentration, catalyst presence, and surface area. The color of reactants is not a factor that affects how fast molecules react.

EmSAT Practice Test

EmSAT Practice Test

EmSAT EmSAT Chemistry 3