Explanation

- In solids, molecules are tightly packed and held by strong intermolecular forces, giving solids a definite shape and volume.  

- Gases have the weakest intermolecular forces.

Explanation

Three types of concave lenses:

1. Bi-concave Lens:

This lens has two surfaces that are curved inward, resembling a double concave shape.

It is the most common type of concave lens and diverges light rays symmetrically from both sides. 

2. Plano-concave Lens:

This lens features one flat surface and one concave surface.

The flat side is known as a "plano" surface. 

3. Convexo-Concave Lens:

Also called a menisco-concave lens, this type has one convex (outward-curving) surface and one concave (inward-curving) surface.

For it to be a concave lens, the concave surface must have a greater curvature than the convex surface, which is moving away from the other. 

Explanation

The human arm acts as a third-class lever, where the effort is applied between the fulcrum (elbow) and the load (hand).  

For example, the forearm is a 3rd class lever because the biceps pulls on the forearm between the joint (fulcrum) and the ball (load).

Using the standard terminology of levers, the forearm is the lever, the biceps tension is the effort, the elbow joint is the fulcrum, and the ball weight is the resistance.

Explanation

- Boyle’s Law: P ∝ 1/V (at constant temperature)  

  → When pressure increases, volume decreases, and vice versa.  

- Applies to gases with constant temperature and fixed mass.  

- Used in understanding gas compression, breathing, and syringe function.

Explanation

Magnetic lines of force always form closed loops from the north pole to the south pole outside the magnet and continue inside the magnet.

They never start or end abruptly like electric field lines.

Explanation

The shopkeeper has charged me ten rupees for this book

We use "for" in this sentence because it shows the purpose or reason for the charge.

for" links the amount to the thing or service you are paying for.

Explanation

Nelson Mandela was deprived of his freedom. 

We use "of" after "deprived" because:

The phrase "deprived of" means to be denied or stripped away something.  

 "Of" shows what exactly is being taken away or denied.

Explanation

The phrase accustomed ended with “To” and is  followed by “ing” form of a verb.

Accustomed to something means کسی چیز کا عادی ہونا

He is accustomed to hot weather means وہ گرم موسم کا عادی ہے۔

Explanation

If the focal length (f) of a mirror is positive, the mirror is a convex mirror.

This is because, according to the sign convention for mirrors,

The focal point of a convex (or diverging) mirror is located behind the mirror,

This is considered the positive direction, leading to a positive focal length. 

Explanation

Negative q means the image forms on the same side as the object — a virtual image.