What are the solutions to these multiple-choice questions about physics?

Here are the solutions to the multiple-choice questions:

1. According to the Newton's Law of universal gravitation force $\propto$:

   • Newton's Law of Universal Gravitation states that the force $F$ is directly proportional to the product of the masses ($m_1 m_2$) and inversely proportional to the square of the distance ($1/r^2$).
   • Therefore, both (A) $m_1 m_2$ and (B) $\frac{1}{r^2}$ are correct proportionality factors.
   • D) Both (A) and (B)

2. The spring in brakes and clutches are used:

   • Springs in brakes and clutches are primarily used to return components to their original position after being actuated.
   • A) To restore original position

3. Newton's first law of motion is also known as law of:

   • Newton's first law of motion describes the property of inertia, where an object resists changes to its state of motion.
   • C) Inertia

4. Stability of a racing car is increased by:

   • Lowering the center of gravity increases the stability of a vehicle, making it less likely to tip over.
   • D) Lowering its centre of gravity

5. A body is in unstable equilibrium after slight till if its center of gravity:

   • In unstable equilibrium, a slight tilt causes the center of gravity to be lowered, and the body continues to move away from its original position, often toppling. If the center of gravity "passes over the point of contact," it means the body will topple.
   • C) Passes over the point contact

6. Quantity of matter contained in body is called:

   • Mass is the measure of the amount of matter in an object.
   • A) Mass

7. Length, mass, electric current, time intensity of light and amount of substance are examples of:

   • These are the seven fundamental quantities in the International System of Units (SI).
   • A) Base quantities

8. Linear thermal expansion of a solid depends upon:

   • Linear thermal expansion ($\Delta L = L_0 \alpha \Delta T$) depends on the original length ($L_0$), the increase in temperature ($\Delta T$), and the material's properties ($\alpha$, the coefficient of linear expansion).
   • D) All of these

9. Heat is the form of:

   • Heat is a form of energy transfer.
   • C) Energy

10. $\underline{\text{Coal}}$ is not a renewable source of energy.

    • Coal is a fossil fuel, which is a finite, non-renewable energy source. Solar, wind, and geothermal energy are renewable.
    • B) Coal

11. Evaporation can occur at:

    • Evaporation is the process by which a liquid changes into a gas without boiling, and it can occur at any temperature below the boiling point.
    • D) All temperatures

12. If a gas is heated in a sealed cylinder, then:

    • In a sealed cylinder (constant volume), heating a gas increases its temperature, which increases the average kinetic energy of its particles and consequently increases the pressure inside the container (Gay-Lussac's Law).
    • D) All of these