Explanation

1. Mercury

Swift Planet for Mercury

***

2. Venus

Eight planets in the solar system

اس ٹاپک کے متعلق انتہائی اہم سوالات پڑھیں

 Planets

Explanation

The telescope is undoubtedly the most important investigative tool in astronomy.

A celestial body that revolves around a planet is known as a natural satellite.

Explanation

• Fission is the splitting of a nucleus that releases free neutrons and lighter nuclei.
• The fission of heavy elements is highly exothermic which releases about 200 million eV compared to burning coal which only gives a few eV.

Explanation

A device that opposes the flow of electrons in electronic circuits is called a resistor.

It is a passive two-terminal component used to reduce current flow, divide voltage, and perform other functions by creating resistance.

Resistance is measured in ohms (Omega). 

Explanation

• Venus and Mercury are the only planets in the solar system that do not have any natural satellites or moons.
• Likely due to their proximity to the Sun and gravitational influences.

Explanation

The pressure of a gas in a container is affected by:

• Temperature (increases with temperature)
• Volume (decreases with increasing volume)
• Density of gas (increases with density)

However, the material of the container does not directly affect the pressure of the gas.

Explanation

• Dust and gas in the interstellar medium (ISM) can absorb and scatter starlight.
• It leading to a reduction in the brightness of stars as seen from Earth.
• This is known as interstellar extinction.

Explanation

Galvanometer works on electromagnetic principles, where electric current produces a magnetic field.

The interaction between magnetic field and coil causes the needle to deflect, allowing current measurement.

A galvanometer measures small currents.

To measure larger currents, a low resistance (called a shunt) is connected in parallel, converting it into an ammeter.

Explanation

When a meteoroid enters Earth’s atmosphere, it burns and becomes a meteor (shooting star).

If it survives the burn and lands on Earth, it is called a meteorite.

Explanation

Astronomers estimate a star’s age primarily by analyzing its chemical composition—especially the presence of hydrogen and helium.

Older stars generally have fewer heavy elements.