Explanation

Temporary hardness of water is caused by dissolved bicarbonates of calcium and magnesium.

It can be removed by boiling, which decomposes Ca(HCO₃)₂ into insoluble carbonate.

Explanation

Qutub minar constructed by: Qutb Uddin Aibak

Construction of Qutub minar started in: 1199

Construction of Qutb Minar completed by: Iltutmish

Explanation

RADAR is an acronym for Radio Detection and Ranging.

The system works by transmitting high-frequency radio waves, or microwaves (which are a type of radio wave), toward an object.

The waves bounce off the object, and a receiver in the radar system detects the reflected energy, known as an echo.

By measuring the time delay between sending and receiving the signal, the system can calculate the distance and velocity of the object. 

Explanation

Osmosis is the movement of water molecules through a semipermeable membrane from an area of higher water concentration to lower concentration.

It is a vital process in biological systems for maintaining cell balance.

Explanation

• Frequency is the number of occurrences of a repeating event per unit of time.
• The SI unit of frequency is the hertz (Hz).
• 1 Hz = 1 cycle or vibration per second
• Unit: Hz = s⁻¹ (per second)
• Named after physicist Heinrich Hertz
• Used for waves, oscillations, sound, and electromagnetic radiation
• Derivations from other quantities: f = 1 / T
• Dimension T^−1

Explanation

Capitals of Provinces in Pakistan:

1. Sindh: Karachi
2. Punjab: Lahore
3. Khyber Pakhtunkhwa: Peshawar
4. Balochistan: Quetta
5. Gilgit-Baltistan (region): Gilgit
6. Azad Jammu and Kashmir (region): Muzaffarabad

Explanation

Velocity SI units: meters per second (m/s or m·s⁻¹).

This unit is derived from the SI units for displacement (meter) and time (second),

Velocity is defined as the rate of change of displacement over time (displacement/time). 

Explanation

Radon (Rn) is a radioactive gas formed from the decay of uranium and radium found in rocks and soil.

He (Helium): Helium is present in trace amounts in the atmosphere.

Ne (Neon): Neon is also present in trace amounts in the atmosphere.

Ar (Argon): Argon is the most abundant noble gas in Earth's atmosphere, making up about 0.93% of the air. 

Explanation

A central force always acts along the line joining the object and a fixed point (the center).

Gravitational and centripetal forces are specific examples of central force.

Explanation

• The 4th and 5th periods in the periodic table are known as the long periods.
• These periods contain 18 elements each, making them the longest periods in the periodic table.

Important Points:

• Short periods: 1st and 2nd periods (2 and 8 elements, respectively)
• Long periods: 4th and 5th periods (18 elements each)
• Normal periods: 3rd and 6th periods (8 and 12 elements, respectively)