Explanation

• The Second is a fundamental unit of time in the International System of Units (SI).
• It is one of the seven base units that are used to derive all other units.

Explanation

• Measurement involves comparing an unknown quantity (the measured) with a standard quantity (the unit) to determine its value.
• This process is a fundamental aspect of science and engineering, allowing us to quantify physical properties and phenomena.

Explanation

The temperature within 10 km of the Earth's core is approximately 4000 Kelvin (K).

At such depths, the temperature is incredibly high due to the immense pressure and heat generated by the Earth's core.

Explanation

• Earth is the biggest of all the terrestrial planets.
• It has temperature, weather, atmosphere and many other factors.
• Its surface 30% is covered with land and 70% with water.
• It has only one moon called Luna.

Explanation

• When Earth is between the Moon and the Sun.
• It blocks the sunlight from reaching the Moon, casting a shadow on the Moon.
• This is known as a Lunar Eclipse.

Explanation

• Transparent objects do not form shadows because they allow all light to pass through them.
• So there is no blocking of light to create a shadow.

Explanation

• An iron nail/steel rod can be magnetized by passing an electric current around it, a process known as electromagnetic induction.
• This is the principle behind electromagnets.

Explanation

• Lever, pulley, wedge, wheel, inclined plane, and screw are examples of simple machines.
• These are basic machines that change the direction or magnitude of a force, making it easier to lift, move, or apply force to an object.

There are six types of simple machines:

1. Inclined Plane
2. Lever
3. Wheel and Axle
4. Pulley
5. Wedge
6. Screw

Explanation

• A periscope requires a prism that can reflect light by 90 degrees, allowing the user to see around obstacles or over walls.
• An isosceles right-angled prism, also known as a 45-degree prism, is ideal for this purpose.
• It has two equal sides and a 90-degree angle between them, which allows for total internal reflection and a clear image.

Explanation

The type of gas utilized in refrigerators to chill water is Tetrafluoroethane, also known as R-134a or HFC-134a.