Explanation

• The pitch of a sound wave depends on its frequency.
• Pitch tells us whether a sound is high or low.
• Higher frequency → higher pitch (e.g., whistle).
• Lower frequency → lower pitch (e.g., bass drum).
• Frequency is measured in Hertz (Hz).

Last verified on 11-08-2026

Explanation

• If he works hard, he will pass the examination.
• This is a First Conditional sentence: If + present simple, will + base verb.
• "Will pass" expresses a likely future result if the condition is fulfilled.

Last verified on 28-07-2026

Explanation

• Sir James Chadwick discovered the neutron in 1932.
• He was a British physicist.
• His discovery completed the basic picture of the atomic nucleus.
• He received the Nobel Prize in Physics in 1935 for this discovery.

Additional information:

• J. J. Thomson – Electron (1897)
• Ernest Rutherford – Atomic nucleus (1911) and Proton (1917)

Last verified on 03-07-2026

Explanation

• Mass and Length are base quantities in SI units.
• Length SI Unit: meter (m)
• Mass SI Unit: kilogram (kg)

Additional information:

Base Quantities in SI System:

• Time (second)
• Electric current (ampere)
• Temperature (kelvin)

Last verified on 16-06-2026

Explanation

• Calcium chloride (CaCl₂) is used as a drying agent in a desiccator.
• It absorbs moisture from the air.
• It keeps substances dry and free from water vapor.
• Desiccators are used in laboratories for drying chemicals.
• CaCl₂ is highly hygroscopic.

Last verified 18-06-2026

Explanation

• “Was reading” is past continuous, so the second action should be in simple past.
• “Came” correctly shows a completed action that interrupted the ongoing action.

Last verified on 17-05-2026

Explanation

• Enzymes sometimes need a non-protein component to function properly.
• This non-protein part is called a cofactor.
• If it is loosely attached, it can easily separate from the enzyme.
• Cofactors help enzymes carry out biochemical reactions.
• They may be inorganic ions or organic molecules.

Last verified on 10-04-2026

Explanation

The K orbit, also known as the first electron shell.

• It can hold a maximum of 2 electrons.

The L orbit, also known as the second electron shell.

• It can hold a maximum of 8 electrons.

The M orbit, also known as the third electron shell.

• It can hold a maximum of 18 electrons.

Last verified on 19-03-2026

Explanation

• Engrossed means مشغول
• Absorbed means جذب

Last verified on 01-02-2026

Explanation

The triple point of water is the unique temperature and pressure at which water coexists in all three phases — solid, liquid, and gas — in equilibrium.

Temperature: 273.16 Kelvin

This is used as a fundamental fixed point in defining the Kelvin temperature scale.