Explanation

• Type: Chemical compound
• Formula: H₂O
• Elements: Hydrogen + Oxygen
• Bond: Covalent bond
• Ratio: 2 hydrogen : 1 oxygen

Last verified on 10-06-2026

Explanation

• Chlorine has the smallest atomic radius among the given elements.
• Atomic radius decreases from left to right across a period.
• Period 3 elements: Sodium (Na), Magnesium (Mg), Aluminum (Al), Chlorine (Cl)
• Atomic radius trend: Na > Mg > Al > Cl
• Reason: Increasing nuclear charge across the period

Last verified 10-06-2026

Explanation

• Ibn Zakariya Al-Razi is considered the father of Pediatrics (Child healthcare).
• He was a famous Muslim physician, philosopher, and scientist.
• Field: Medicine, Chemistry, Philosophy
• Known as: Rhazes
• Famous books: Al-Hawi, Kitab al-Mansuri

Last verified on 09-06-2026

Explanation

Hydrogen gas is H₂, molar mass ≈ 2.016 g/mol  

Moles = mass / molar mass  

= 8.064 g / 2.016 g/mol = 4.0 mol

So there are 4 moles of H₂ molecules.

Last verified on 09-06-2026

Explanation

• Iron (Fe) is a trace element required in very small amounts in the body.
• It is essential for forming hemoglobin in blood.
• It helps in oxygen transport in red blood cells.
• Other trace elements include: Zinc, Copper, Iodine, Manganese, Cobalt.

Last verified on 09-06-2026