811.

Assertion : R₃P=O exists but R₃N=O does not exist.

Reason : P is more electronegative than N.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

The basic structural. unit and its geometry in silicates is :

• SiO₂ , tetrahedral

• Si${\mathrm{O}}_4^{4-}$ , square planar

• SiO₂ , square planar

• Si${\mathrm{O}}_4^{4-}$ , tetrahedral

Assertion : Bond energy and bond dissociation energy have identical value for diatomic molecules.

Reason : Greater the bond dissociation energy, less reactive is the bond.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

KF combines with HF to form KHF₂. This compound contains the species

• K⁺, F^- and H⁺

• K⁺, F^- and HF

• K⁺ and [HF₂]^-

• [KHF]⁺ and F₂

The molecules having the same hybridization, shape and number of lone pairs of electrons are

• SeF₄, XeO₂F₂

• SF₄, XeF₂

• XeOF₄, TeF₄

• SeCl₄, XeF₄

The M - O- M bond angles in MO (where M is halogen) is in the order

• Br₂O > Cl₂O > F₂O

• F₂O > Br₂O > Cl₂O

• F₂O > Cl₂O > Br₂O

• Cl₂O > F₂O > Br₂O

The geometry of methane molecule is :

• tetrahedral

• pyramidal

• octahedral

• square planar

Heisenberg's uncertainty principle can be explained as :

• $∆$x $⩾$ $\frac{∆\mathrm{p} \times \mathrm{h}}{4\mathrm{\pi }}$

• $\mathrm{∆}$x x $∆$p $⩾$ $\frac{\mathrm{h}}{4\mathrm{\pi }}$

• $∆$x x $∆$p $⩾$ $\frac{\mathrm{h}}{\mathrm{\pi }}$

• $∆$p $⩾$ $\frac{\mathrm{\pi h}}{∆\mathrm{x}}$

The bond energy is the energy required to :

• dissociate one mole of the substance

• dissociate bond in 1 kg of the substance

• break one mole of similar bonds

• break bonds in one mole of the substance

What is binding energy in ${}_5{}^{11}\mathrm{B}$ nucleus , if mass is 0.08181 amu ?

• 1.2 x 10^-4 erg/nucleus

• 8.2 x 10^-4 erg/nucleus

• 10.2 x 10^-4 erg/nucleus

• 1.9 x 10^-4 erg/nucleus