Explanation

The error is in parallelism: “digestive systems” and “respiratory systems” are nouns, so the third item should also be a noun phrase, not a verb.

Corrected sentence:

"Both plants and animals have digestive systems, respiratory systems, and reproductive systems."

Explanation

The phrase "he or she was dead" contains a grammatical error.

After the verb "wish," we use the subjunctive mood to express hypothetical or unreal situations.

The correct form should be "were" instead of "was."

The corrected sentence would be:

"Even a normal person may temporarily wish that he or she were dead but prolonged depression should not go untreated."

Explanation

Rutherford’s gold foil experiment (1909) showed that atoms have a small, dense, positively charged center.

This center is called the nucleus, where most of the atom’s mass is concentrated.

Explanation

Explanation

Explanation

Argon was discovered in 1894 by Lord Rayleigh and Sir William Ramsay.

It is a noble gas, chemically inert and found in the atmosphere.

Explanation

To determine the slowest rate of diffusion, we use Graham’s law:

Rate of diffusion ∝ 1/√Molar mass

Molar masses:

• O₂ = 32 g/mol
• N₂ = 28 g/mol
• CH₄ = 16 g/mol
• NH₃ = 17 g/mol

Heavier gases diffuse more slowly.

O₂ has the highest molar mass among the options, so its diffusion is slowest.

Explanation

Argon is a commonly used gas used to fill incandescent light bulbs.

It increases bulb life by preventing the tungsten filaments from deteriorating too quickly.

Other gases are also used in lighting such as:

• Helium
• Neon
• Nitrogen
• Krypton

Explanation

Most plastics are derived from petroleum and natural gas, which are non-renewable fossil fuels.

Large-scale plastic production reduces fossil fuel reserves.

Explanation

Potassium (K) has a +1 oxidation state and selenium (Se) has a -2 oxidation state.

Two K⁺ ions combine with one Se²⁻ ion to form K₂Se.