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1101.

Element `X` is strongly electropositive and element `Y` is strongly electronegative. Both are univalent. The compound formed would beA. `X^+ Y^-`B. `X^(- ) Y^(+)`C. `X-Y`D. `X to Y`

Answer» Correct Answer - A
lonic compound `X^(+) Y^(-)`.
Discussion
1102.

In X - H----Y , both X and Y are electronegative elementsA. electron density on X will increase and on H will decreaseB. in both electron density will increaseC. in both electron density will decreaseD. on X electron density will decrease and on H increase

Answer» Correct Answer - A
In X-H ---- Y, X and Y both are electronegative elements , then electron density on X will increase and on H will decrease.
Discussion
1103.

Although `Na^(2+)` has a higher charge and, therefore, `NaCl_2` should have a greater lattice enthalpy, sodium prefers to form `NaCl` rather than `NaCl_2` becauseA. `Delta_iH_2` of `Na` is very highB. the lattice enthalpy of `NaCl_2` is far too small to compensate for the energy required to produce the `Na^(2+)` ionC. `Na^(2+)` does not have the noble gas electron configurationD. the lattice enthalpy of `NaCl_2` is less than the lattice enthalpy of `NaCl`

Answer» Correct Answer - B
Sum of `Delta_iH_1` and `Delta_iH_2` for `Na` is `(496 kJ mol^(-1)+4560 kJ mol^(-1))5056 kJ mol^(-1)` while the lattice enthalpy of hypothetical `NaCl_2` is `2527 kJ mol^(-1)` (assuming roughly the same as that for `MgCl_2`). It is far too small an energy yield to compensate for the energy required to produce `Na^(2+)` ion. Using similar reasoning, we can explain that `Na_2Cl` does not exist as its lattice enthalpy is not able to compensate the energy needed to form `Na^(+)` and `Cl^(2-)`.
Discussion
1104.

Although for `Mg`, `Delta_iH(378 kJ mol^(-1))` is greater than `Delta_iH_2 (1450 kJ mol^(-1))`, `Mg` prefers to form `MgCl_2` rather than `MgCl` becauseA. `Mg^(2+)` ion has the noble gas configurationB. `Mg^(2+)` ion is smaller than `Mg^(+)`C. `Mg^(2+)` ion has higher charge than `Mg^(+)` ionD. the lattice enthalpy of `MgCl_2` is very high

Answer» Correct Answer - D
Lattice enthalpy of `MgCl_2(2527 kJ mol^(-1))` is more than enough to compensate for the energy needed to remove the first two electrons from an `Mg` atom (`738 kJ mol^(-1)+1450 kJ mol^(-1)=2188 kJ mol^(-1)`).
Discussion
1105.

In terms of polar character, which of the following order is correct ?A. `NH_(3) lt H_(2)O lt HF lt H_(2)S`B. `H_(2)S lt NH_(3) lt H_(2)O lt HF`C. `H_(2)O lt NH_(3) lt H_(2)S lt HF`D. `HF lt H_(2)O lt NH_(3) lt H_(2)S`

Answer» Correct Answer - B
An electronegativity difference of bond increases, polar character also increases.
Discussion
1106.

Statement I `LiCl` is predomionantly a covalent compound. Statement II Electronegatvity difference between `Li` and `Cl` is too smallA. Statement I is true: Statement II is true, Statement II is the correct explanation of Statement I.B. Statement I is true, Statement II is true, Statement II is not the correct explanation of Statement I.C. Statement I is true, Statement II is false.D. Statement I is false, Statement II is true.

Answer» Correct Answer - c
Discussion
1107.

Statement I `LiCl` is predomionantly a covalent compound. Statement II Electronegatvity difference between `Li` and `Cl` is too smallA. If both assertion and reason are true and the reason is the correct explanation of the assertionB. if both assertion and reason are true but reason is not the correct explanation of the assertionC. if assertion is true but reason is falseD. if the assertion and reason both are false

Answer» Correct Answer - C
LiCl is a covalent compound since due to the larger size of the anion (`Cl^(-)`) is effective nuclear charge lessens and its valence shells are held tightly towards its nucleaus. Here, assertion is correct but reason is incorrect.
Discussion
1108.

Which molecule is depicted by the given ball and stick models ? A. `(i) BeCl_(2), (ii) CH_(4)`B. `(i) BF_(3), (ii) PCl_(5)`C. `BF_(4), (ii) CH_(4)`D. `Be Cl_(2), (ii) PCl_(5)`

Answer» Correct Answer - B
`BF_(3)` - Trigonal planar with bond angle `120^(@)`.
`PCl_(5)` - Trigonal bipyramidal with bond angles `120^(@) and 90^(@)`.
Discussion