Which one of the following will have largest number of atoms?
(i) 1 g Au (s)
(ii) 1 g Na (s)
(iii) 1 g Li (s)
(iv) 1 g of Cl2(g)
(i) Gram atomic mass of Au= 197 g
Or
197g of Au contains = 6.022 x 1023
Therefore 1gm of Au contains = 6.022 x 1023/197*1 = 3.06 x 1021 atoms
(ii) Gram atomic mass of Na = 23 g
Or
23 g of Na contains atoms = 6.022x 1023
Or
1gm of Na contains atoms = 6.022x1023 /23 *1 = 26.2 x1021 atoms
(iii) Gram atomic mass of Li = 7
Or
7g of Li contains atoms = 6.022 x 1023
Or
1g of Li contains atoms = 6.022 x 1023/7 *1= 86.0 x 1021 atoms
(iv) Gram atomic mass of Cl = 71 Or 71g of Cl contains atoms = 6.022x1023
Or
1 g of Cl contains atoms = 6.022x1023 /71 * 1= 8.48 x 1021 atoms
Hence, 1 g of Li (s) will have the largest number of atoms.
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
Calculate the amount of carbon dioxide that could be produced when
(i) 1 mole of carbon is burnt in air.
(ii) 1 mole of carbon is burnt in 16 g of dioxygen.
(iii) 2 moles of carbon are burnt in 16 g of dioxygen.
Calculate the wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
Balance the following redox reactions by ion – electron method :
(a) MnO4 – (aq) + I – (aq) → MnO2 (s) + I2(s) (in basic medium)
(b) MnO4 – (aq) + SO2 (g) → Mn2+ (aq) + HSO4– (aq) (in acidic solution)
(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O7 2– + SO2(g) → Cr3+ (aq) + SO42– (aq) (in acidic solution)
In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.
(i) 300 atoms of A + 200 molecules of B
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules of B
(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B
At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?
Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?
What is meant by the term bond order? Calculate the bond order of: N2, O2,O2+,and O2-.
The bromine atom possesses 35 electrons. It contains 6 electrons in 2p orbital, 6 electrons in 3p orbital and 5 electrons in 4p orbital. Which of these electron experiences the lowest effective nuclear charge?
Explain the formation of H2 molecule on the basis of valence bond theory.
The pH of 0.1M solution of cyanic acid (HCNO) is 2.34. Calculate the ionization constant of the acid and its degree of ionization in the solution.
2 × 108 atoms of carbon are arranged side by side. Calculate the radius of carbon atom if the length of this arrangement is 2.4 cm.
Why are potassium and cesium, rather than lithium used in photoelectric cells?
The ejection of the photoelectron from the silver metal in the photoelectric effect experiment can be stopped by applying the voltage of 0.35 V when the radiation 256.7 nm is used. Calculate the work function for silver metal.
In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?
Classify the following species into Lewis acids and Lewis bases and show how these act as Lewis acid/base:
(a) OH–
(b) F–
(c) H+
(d) BCl3
What is the SI unit of mass? How is it defined?
Find energy of each of the photons which
(i) correspond to light of frequency 3× 1015 Hz.
(ii) have wavelength of 0.50 Å.
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