31.

Both Co³⁺ and Pt⁴⁺ have a coordination number of six. Which of the following pairs of complexes will show approximately the same electrical conductance for their 0.001M aqueous solutions?

• CoCl₃ · 4NH₃ and PtCl₄ . 4NH₃

• CoCl₃ · 3NH₃ and PtCl₄ · 5NH₃

• CoCl₃ · 6NH₃ and PtCl₄  · 5NH3

• CoCl₃ . 6NH₃ and PtCl₄ . 3NH₃

The cubic unit cell of Al (molar mass 27 g mol^-1) has an edge length of 405 pm. Its denstiy is 2.7g cm^-3. The cubic unit cell is

• face centred

• body centred

• primitive

• edge centred

The radioactive isotope of caesium -137 of weight 8 g was collected on 1^st February, 2006 and kept in a sealed tube. On 1^st July 2006 it was found that only 0.25 g of it remained. The half-life period of the isotope is

• 37.5 day

• 30 day

• 25 day

• 50 day

Which of the following make up an isotonic triad?

• ${}_{32}{}^{78}\mathrm{Ge}, {}_{33}{}^{77}\mathrm{As}, {}_{31}{}^{74}\mathrm{Ga}$

• ${}_{18}{}^{40}\mathrm{Ar}, {}_{19}{}^{40}\mathrm{K}, {}_{20}{}^{40}\mathrm{Ca}$

• ${}_6{}^{14}\mathrm{C}, {}_8{}^{16}\mathrm{O}, {}_7{}^{15}\mathrm{N}$

• ${}_6{}^{13}\mathrm{C}, {}_7{}^{12}\mathrm{C}, {}_7{}^{14}\mathrm{N}$

The age of a specimen t is realted to the daughter/ parent ratio of number of atoms (D/ P) by the equation (λ = decay constant)

• t = $\frac{1}{\mathrm{\lambda }} \ln \left\{\frac{\mathrm{D}}{\mathrm{P}}\right\}$

• t = $\frac{1}{\mathrm{\lambda }} \ln \left\{1 + \frac{\mathrm{P}}{\mathrm{D}}\right\}$

• t = $\frac{1}{\mathrm{\lambda }} \ln \left\{2 + \frac{\mathrm{P}}{\mathrm{D}}\right\}$

• t = $\frac{1}{\mathrm{\lambda }} \ln \left\{1 + \frac{\mathrm{D}}{\mathrm{P}}\right\}$

Which one of the following set of units represents the smallest and largest amount of energy respectively?

• J and erg

• erg and cal

• cal and eV

• eV and lit-atom

The effciency of enzyme catalysis is due to its capacity to

• form a strong enzyme-substrate complex

• chage the shape of the substrate

• lower the activation energy of the reaction

• form a colloidal solution in water

Under which one of the following conditions, does the reaction

CH ≡ CH + CH₃OH $\stackrel{?}{\to }$ CH₃O-CH=CH₂ take place?

• NH₄OH/ 80°C

• conc. H₂SO₄ / 160°C

• CH₃OK/ 160- 200°C

• Dilute HCl/ THF, 80°C

Identify the product/s in the following reaction

3CH₃CH = CH₂ $\stackrel{{\mathrm{BH}}_3}{\to }$ X $\stackrel{{\mathrm{H}}_2{\mathrm{O}}_2/ {\mathrm{OH}}^{-}}{\to }$ Product/s + H₃BO₃

• CH₃CH₂CH₂OH

• CH₃CHOCH₃

• CH₃CH₂CHO

• CH₃CH₂OH + CH₃OH

Which of the following is not true of carbanions?

• The carbon carrying the charge has eight valence electrons

• They are formed by heterolytic fission

• They are paramagnetic

• The carbon carrying the charge is sp³ hybridised