Explanation

• A true solution is a homogeneous mixture in which the solute is completely dissolved in the solvent at the molecular level. 
• The particles are very small and cannot be seen with the naked eye. 
• True solutions are stable and do not settle down on standing.

Examples of true solutions (homogeneous mixtures):

• Salt in water (NaCl solution)
• Sugar in water
• Vinegar in water
• Alcohol in water
• Copper sulfate in water

Last verified on 15-03-2026

Explanation

• According to Albert Einstein, light travels in the form of photons, which are tiny packets (quanta) of energy.
• This concept was proposed in 1905 while explaining the photoelectric effect.
• Photons behave like particles but also show wave properties.

Last verified on 15-03-2026

Explanation

• Valency is the combining capacity of an atom to form molecules or compounds.
• It depends on the number of electrons an atom can lose, gain, or share to complete its outer shell.

Last verified on 15-03-2026

Explanation

• All plants move Anticlockwise around Sun.
• All plants move anticlockwise around their axis.
• Earth rotates its axis from West to East.

Last verified on 15-03-2026

Explanation

• Fluoride is commonly added to drinking water in small amounts to prevent tooth decay (dental cavities).
• It strengthens tooth enamel and makes teeth more resistant to acid attacks from bacteria and sugars.
• Community water fluoridation began in 1945 in the United States as a public health measure.

Last verified on 15-03-2026

Explanation

• Mitochondria are cell organelles responsible for producing energy in the form of ATP (Adenosine Triphosphate) through cellular respiration. 
• They are called the “Powerhouse of the cell” because they provide the energy required for all cellular activities.
• Mitochondria have their own DNA and ribosomes, allowing them to replicate independently.

Last verified on 14-03-2026

Explanation

Work done (W) by a force is calculated as:

W = F × d × cosθ.

• F = force applied
• d = displacement of the body
• θ = angle between force and displacement

When θ = 0° (force parallel to motion), cos 0° = 1, so work done is maximum.

Last verified on 14-03-2026

Explanation

• Manchar Lake is the largest natural lake in Pakistan.
• It is part of the Indus River basin.
• Covered Area: ~260 km² (100 square miles)
• Location: Jamshoro District, Sindh
• Water Source: Kirthar Mountains and surrounding streams

Last verified on 14-03-2026

Explanation

• The Sukkur Barrage, officially named Lloyd Barrage, is located in Sindh Province.
• It built from 1923 to 1932 during the British Raj.
• It was rehabilitated in November 2004. 
• The barrage is approximately 2 km (1 mi) long.
• It is the oldest in Pakistan, with seven canals taking off from it.

Last verified on 14-03-2026

Explanation

While means during the time that something is happening.

After means later than or following a particular time, which is the opposite idea.

• While means اس وقت کے دوران جب کچھ ہو رہا ہے۔
• After means کسی خاص وقت کے بعد یا اس کے بعد

Last verified on 14-03-2026