Explanation

• The complete transfer of one or more electrons from one atom to another atom forms an ionic bond.
• This type of bond is characterized by the electrostatic attraction between two ions with opposite charges, typically a metal cation and a nonmetal anion.
• The atom that loses an electron becomes a positively charged ion (cation), while the atom that gains an electron becomes a negatively charged ion (anion).

Explanation

When two or more atoms chemically bond together, they form a molecule.

Examples include H₂ (hydrogen molecule) and O₂ (oxygen molecule).

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)

Explanation

Fertilizers rich in nitrogen are called nitrogenous fertilizers (e.g., urea, ammonium nitrate).

They are mainly used to promote leafy and vegetative growth in plants.

Explanation

Urea is the most widely used nitrogenous fertilizer in Pakistan due to its high nitrogen content (46%).

It is cheap, effective, and easily available compared to other nitrogen fertilizers.

Explanation

Neon is a noble gas that exists as single atoms (mono-atomic) in nature.

Oxygen (O₂), Nitrogen (N₂), and Fluorine (F₂) are diatomic molecules.

Explanation

In shade, temperature is lower, so water molecules gain less energy to escape into vapor.

Hence, evaporation is slower compared to direct sunlight.

Explanation

DAP (Diammonium Phosphate) is a synthetic chemical fertilizer rich in nitrogen and phosphorus.

Manures and compost are natural fertilizers, not synthetic.

Explanation

Most organic compounds are non-polar, so they dissolve in non-polar solvents like ether, petroleum, and benzene.

Water is polar, so organic compounds are generally insoluble in it.

Explanation

Hydrogen is the lightest element, and its relative atomic mass is approximately 1.00794 amu.

This value is based on the average isotopic composition of hydrogen (mainly protium, deuterium, and a trace of tritium).