A 250 W electric bulb of 80% efficiency emits a light of 6626 Å wavelength. The number of photons emitted per second by the lamp is (h = 6.636 x 10-34 Js)
1.42 × 1017
2.18 × 1016
6.66 × 1020
2.83 × 1016
The work function of a metal is 5 eV. What is the kinetic energy of the photoelectron ejected from the metal surface if the energy of the incident radiation is 6.2 eV? (1 eV = 1.6 × 10-19)
1.92 × 10-19 J
6.626 × 10-19 J
8.10 × 10-19 J
1.92 × 10-18 J
The lattice energy of NaCl is 788 kJ mol-1. This means that 788 kJ of energy is required
to separate one mole of solid NaCl into one mole of Na (g) and one mole of Cl (g) to infinite distance
to separate one mole of solid NaCl into one mole of Na+ (g) and one mole of Cl- (g) to infinite distance
to convert one mole of solid NaCl into one mole of gaseous NaCl
to convert one mole of gaseous NaCl into one mole of solid NaCl
Which one of the following statements is not true in respect of propeties of interhalogen compounds?
They are all covalent compounds
They are volatile solids or liquids except ClF
IF5 has square pyramidal structure
They are all paramagnetic in nature
D.
They are all paramagnetic in nature
Interhalogen compounds are covalent molecules. With the exception of CIF (which is a gas at 298 K), all are volatile solids or liquids. They are diamagnetic in nature. The shape of IF5 is square pyramidal. These compounds are very useful flourinating agents. e.g., ClF3 and BrF3 are used for production of UF6 in the enrichment of 235U.
An aqueous solution containing 3 g of a solute of molar mass 111.6 g mol-1 in a certain mass of water freezes at -0.125°C. The mass of water in grams present in the solution is (Kf =1.86 K kg mol-1)
300
600
500
400
The change in potential of the half-cell Cu2+|Cu when aqueous Cu2+ solution is diluted 100 times at 298 K?
increases by 120 mV
decreases by 120 mV
increases by 60 mV
decreases by 60 mV
Consider the following elecrolytic cells
(i) M (s) | M2+ (aq), 0.1 M || X2+ (aq), 0.01 M | X (s)
(ii) M (s) | M2+ (aq), 0.1 M || X2 (aq), 0.01 M | X (s)
(iii) M (s) | M2+ (aq), 0.1 M || X2 (aq), 0.01 M | X (s)
The cell EMF of the above cells are E1, E2 and E3 respectively. Which one of the following is true?
E3 > E2 > E1
E1 > E2 > E3
E2 > E3 > E1
E1 > E3 > E2
The correct decreasing order of reactivity for a given alkyl (R) group in both SN1 and SN2 reaction mechanisms is
R - I > R - Br > R - Cl > R - F
R - I > R - Cl > R - Br > R - F
R - F > R - Cl > R - Br > R - I
R - F > R - I > R - Cl > R - Br
The compound of molecular formula C5H10O(A) reacts with Tollen's reagent to give silver mirror but does not undergo aldol condensation. The compound A is
3-pentanone
2, 2-dimethylpropanal
3-hydroxy-2-pentene
3-methylbutanal
Chloroform reacts with oxygen in the presence of light to give
carbon tetrachloride
carbonyl chloride
methyl chloride
acetaldehyde