Correct Answer: Infrared waves are largely absorbed by water vapor that is concentrated in the lower atmosphere.

Explanation:

1. “The total amount of insolation received at the equator is roughly about 10 times that received at the poles.”
   Incorrect.
   While there is a significant difference in insolation between the equator and the poles due to the angle of incidence of solar radiation, it is not as extreme as 10 times. The actual difference is much smaller, generally ranging from 2 to 3 times.
2. “Infrared rays constitute roughly two-thirds of insolation.”
   Incorrect.
   Infrared rays are part of the electromagnetic spectrum, but they only constitute a small portion of the incoming solar radiation (insolation). The majority of insolation consists of visible light and ultraviolet radiation.
3. “Infrared waves are largely absorbed by water vapor that is concentrated in the lower atmosphere.”
   Correct.
   Infrared waves, which are long-wavelength radiation, are absorbed by greenhouse gases such as water vapor, carbon dioxide, and methane. Water vapor, concentrated in the lower atmosphere (troposphere), plays a major role in absorbing and trapping infrared radiation, contributing to the greenhouse effect.
4. “Infrared waves are a part of the visible spectrum of electromagnetic waves of solar radiation.”
   Incorrect.
   Infrared waves are not part of the visible spectrum. The visible spectrum includes wavelengths between 400-700 nanometers, whereas infrared waves are longer than this range and are not visible to the human eye.

Let’s evaluate the two statements:

Statement 1:

• Ballistic missiles are typically rocket-propelled and follow a parabolic trajectory that reaches the upper atmosphere before re-entering and hitting the target at high speeds, often supersonic or hypersonic.
• Cruise missiles, on the other hand, are typically powered by jet engines throughout their flight, allowing them to travel at subsonic or supersonic speeds, depending on the type of missile. They do not rely on rockets for propulsion after launch.

The statement that ballistic missiles are jet-propelled at subsonic speeds throughout their flight and cruise missiles are rocket-powered only in the initial phase is incorrect. In fact, it should be the other way around: Ballistic missiles are rocket-propelled throughout their flight, while cruise missiles are jet-powered for most of their flight.

Statement 2:

• Agni-V is a long-range ballistic missile, not a cruise missile. It is capable of carrying nuclear warheads and has a range of around 5,000 km, making it an intercontinental ballistic missile (ICBM).
• BrahMos is a supersonic cruise missile, not an intercontinental ballistic missile (ICBM). It is a joint venture between India and Russia and is one of the fastest cruise missiles in the world.

Therefore, Statement 2 is also incorrect.

Conclusion:

Both statements are incorrect.

The correct answer is: Neither 1 nor 2.

Let’s evaluate the pairs one by one:

1. Cepheids: These are stars that brighten and dim periodically due to changes in their size and temperature. The description in the pair refers to stars and not to giant clouds of dust and gas. Hence, this pair is incorrect.
2. Nebulae: Nebulae are giant clouds of dust and gas in space, not stars that brighten and dim periodically. The description in the pair is incorrect. Hence, this pair is incorrect.
3. Pulsars: Pulsars are indeed neutron stars that emit beams of radiation, and they are formed when massive stars run out of fuel and collapse. The description in the pair is accurate. Hence, this pair is correct.

Therefore, only one of the pairs is correctly matched.

The answer is: Only one.

The correct answer is All three.

Here’s how an accelerometer is involved in each action:

1. Detection of Car Crash/Collision

• An accelerometer detects rapid deceleration or impact forces, which triggers the deployment of airbags almost instantaneously.
• Function of accelerometer: Required.

2. Detection of Free Fall of a Laptop

• Accelerometers sense sudden free-fall motion (near-zero acceleration in free fall) and can signal the hard drive to turn off immediately to prevent damage.
• Function of accelerometer: Required.

3. Detection of Tilt of a Smartphone

• Accelerometers measure the tilt or orientation of the device relative to gravity, allowing the display to rotate between portrait and landscape modes.
• Function of accelerometer: Required.

An accelerometer is required in all three actions, as it plays a crucial role in detecting motion, orientation, or force changes in each scenario. Thus, the correct answer is All three.