In the formation of ammonium ion (NH₄⁺) from NH₃ and H⁺, the type of bond formed is:
A. Hydrogen bond
B. Covalent bond
C. Coordinate bond
D. Ionic bond
Answer: Option C
Solution (By JKExamLibrary)
NH₃ has a lone pair on nitrogen, which it donates to the empty 1s orbital of H⁺, forming a coordinate (dative) bond where both electrons come from nitrogen. The resulting NH₄⁺ has four equivalent N–H covalent bonds and a +1 charge. Coordinate bonds are common in complex ions: e.g., [Ag(NH₃)₂]⁺. Once formed, a coordinate bond is indistinguishable from a covalent bond.
Explanation:
Graham's law: r ∝ 1/√M (molar mass). At same T,P, rate inversely proportional to square root of density. Lighter gases diffuse faster. Used in uranium enrichment (UF₆).
Explanation:
When cement hydrates, it releases heat known as heat of hydration. This exothermic process can cause thermal cracking in massive concrete structures if not controlled. The main compounds C₃S and C₃A have high heat of hydration. For dams, low-heat cement with lower C₃A content is used. Heat of solution is for dissolving, combustion for burning, fusion for melting.
Assertion (A): The Montreal Protocol was signed to control the emission of CFCs. Reason (R): CFCs are responsible for the depletion of the ozone layer.
A.Both A and R are true but R is NOT the correct explanation of A.
B.A is true but R is false.
C.A is false but R is true.
D.Both A and R are true and R is the correct explanation of A.
Explanation:
The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances responsible for ozone depletion, most notably chlorofluorocarbons (CFCs). Both statements are correct, and R perfectly explains the purpose of the protocol.
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