A gas at constant temperature expands from 10 L to 20 L. What happens to its pressure?
A. Halves
B. Doubles
C. Remains same
D. Becomes zero
Answer: Option A
Solution (By JKSSB Mock Tests)
Boyle's law: P₁V₁ = P₂V₂. So P₂ = P₁(V₁/V₂) = P₁(10/20) = P₁/2. Pressure is halved. If volume doubles, pressure halves, assuming constant temperature and amount. This is an inverse relationship.
Explanation:
Boron trifluoride (BF₃) has covalent bonds where boron shares three electrons with three fluorine atoms. Although BF₃ can accept a lone pair to form coordinate bonds (as in BF₄⁻), its own bonds are polar covalent. Ionic bonding occurs between metal and non-metal.
Explanation:
Across period 3, nuclear charge increases (Na: 11+, Cl: 17+) while electrons are added to the same shell. The increased attraction pulls electrons closer, decreasing radius. Na has larger radius despite having fewer electrons.
Assertion (A): The first ionization energy of Nitrogen is higher than that of Oxygen. Reason (R): Nitrogen has a half-filled p-orbital which is exceptionally stable.
A.Both A and R are true and R is the correct explanation of A.
B.Both A and R are true but R is NOT the correct explanation of A.
Explanation:
Nitrogen (1s2 2s2 2p3) has a exactly half-filled p-subshell, which confers extra stability due to symmetry and exchange energy. Oxygen (1s2 2s2 2p4) has one paired electron in the p-orbital, leading to electron-electron repulsion, making it easier to remove. Thus, N has a higher IE than O. Both are true and R explains A.
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