Explanation

The atomic number (proton number) determines the element.

Both X (₁₉) and Y (₁₉) have the same proton number 19, so they represent the same element but different isotopes.

• ⁴⁰₁₉X → Proton number = 19, Mass number = 40
• ³⁹₁₉Y → Proton number = 19, Mass number = 39
• ³⁸₂₀Z → Proton number = 20, Mass number = 38

Last verified on 15-03-2026

Explanation

• Phosphorus molecule naturally exists as P₄.
• It means one molecule contains four phosphorus atoms bonded together.
• This form is commonly found in white phosphorus, where the atoms form a tetrahedral structure.

Additional information:

• O₂ – Oxygen molecule
• N₂ – Nitrogen molecule
• H₂ – Hydrogen molecule
• Cl₂ – Chlorine molecule

Last verified on 15-03-2026

Explanation

• The symbolic representation of a molecule of a compound is called a formula.
• It uses symbols and numbers to represent the composition of the molecule.
• For example, the formula for water is H₂O, indicating two hydrogen atoms and one oxygen atom.

Last verified on 15-03-2026

Explanation

The highest power of y is 3, so the equation is cubic in y.

The term 3x² is quadratic in x, but overall the highest degree is 3.

This making it a cubic equation.

Last verified on 15-03-2026

Explanation

Area of square = side × side

225 = side²

Taking square root on both sides:

side = √225 = 15 meters

Last verified on 15-03-2026

Explanation

Plugging in the values:

x² + y² = (4)² + (-2)²

= 4 × 4 + (-2) × (-2)

= 16 + 4

= 20

Last verified on 15-03-2026

Explanation

Total ratio parts = 2 + 3 + 5 = 10

A's ratio = 2

A's investment = (2/10) × 12 lac = 2.4 lac

Last verified on 15-03-2026

Explanation

Counting the place values from right to left:

2 (ones), 6 (tens), 4 (hundreds), 0 (thousands), 8 (ten-thousands), 4 (hundred-thousands), 4 (millions), 2 (ten-millions)

The 8 is in the ten-thousands place, so its value = 8 × 10,000 = 80,000.

Last verified on 15-03-2026

Explanation

A 7-digit number like 1,000,000 represents one million.

In Pakistani numbering system, it's also referred to as "Ten Lakh".

Last verified on 15-03-2026

Explanation

CP = 80, SP = 100

Profit = 100 - 80 = 20

Profit% = (20/80) × 100 = 25%

Last verified on 15-03-2026