EmSAT Chemistry

Question 1

What is the atomic number of carbon?

Accepted Answer

6

Answer

Carbon has atomic number 6, meaning it has 6 protons in its nucleus. The mass number of carbon-12 is 12 (6 protons + 6 neutrons).

Question 2

What type of bond is formed when electrons are shared between two nonmetal atoms?

Accepted Answer

Covalent bond

Answer

Covalent bonds form when two nonmetal atoms share electron pairs. Ionic bonds involve electron transfer, typically between metals and nonmetals.

Question 3

What is the pH of a neutral solution at 25°C?

Accepted Answer

7

Answer

At 25°C, a neutral solution has a pH of 7, where the concentration of H⁺ ions equals the concentration of OH⁻ ions (each at 10⁻⁷ M).

Question 4

How many moles of water are produced when 2 moles of hydrogen gas react with 1 mole of oxygen gas?

Accepted Answer

2 moles

Answer

The balanced equation 2H₂ + O₂ → 2H₂O shows that 2 moles of H₂ reacting with 1 mole of O₂ produces 2 moles of H₂O.

Question 5

Which of the following is an example of a physical change?

Accepted Answer

Melting ice

Answer

Melting ice is a physical change because only the state of matter changes (solid to liquid) — the chemical composition (H₂O) remains the same. The other options involve chemical changes.

EmSAT Practice Test

EmSAT Practice Test

EmSAT Chemistry