Test: Materials and Their Structure - Grade 9 MCQ

Neutrons are neutral particles found in the nucleus, unlike protons (positive) and electrons (negative).

J.J. Thomson discovered the electron in the late 1800s and proposed the plum pudding model.

The composition of salts in seawater shows sodium chloride is 68% of the total salts.

Earth’s atmosphere is about 78% nitrogen, making it the most abundant gas.

Rutherford’s gold foil experiment showed atoms are mostly empty space with a dense, positively charged nucleus.

Tropical zones have consistently high temperatures and humidity.

18 parts of gold out of 24 means (18 ÷ 24) × 100 = 75% purity.

In 1932, James Chadwick discovered neutrons, refining the atomic model.

Weather is defined by atmospheric conditions like temperature, humidity, wind, and precipitation, not soil type.

Peer review allows other scientists to check the accuracy and reliability of findings through repeated testing.