Q1.In which case purity of the substance is 100%?
(a)1 mol of CaCO3 gave 11.2 L CO2
(b)1 mol of MgCO3 gave 40g MgO
(c)1 mol of NaHCO3 gave 4 g H2O
(d)1 mol of Ca(HCO3)2 gave 1 mol CO2
Q.2 M2+ is isoelectronic of SO2 and has (Z+2) neutrons (Z is atomic no. of M).Thus ionic mass of M2+ is -
(a)70 (b)66 (c)68 (d)64
Q.3 X-- ,Y2-- and Z3-- are isotonic and isoelectronic.Thus,increasing order of atomic number of X,Y and Z is
(a)X<Y<Z
(b)Z<Y<X
(c)X=Y=Z
(d)Z<X<Y
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3 Answers
106Q3. as X-, Y2- and Z3- are isoelectronic
Therefore if u take out 3 electrons from Z, 2 electrons from Y and 1 electron from X u will get the neutral atom.
Hence atomic no. of X>Y>Z
106Q2. M2+ is isoelectronic with SO2 which has (16+2*8) = 32 electrons
Hence M has 34 electrons i.e. its atomic no. is 34
So, no. of protons = 34
and no. of neutrons = 34+2 = 36
Hence ionic mass of M2+ = atomic mass of M = 34+36 = 70
106Q1. (a) CaCO3 --> CaO + CO2
1 mol 1 mol = 22.4 lit hence (a) is wrong
(b) MgCO3 --> MgO + CO2
1 mol 1 mol = 40 gm hence (b) is correct
(c) 2NaHCO3 --> Na2CO3 + H2O + CO2
2 mole 1 mol
1 mole 0.5 mol = 9g hence (C) is wrong
(d) Ca(HCO3)2 --> CaCO3 + H2O + CO2
1 mole 1 mol hence (d) is correct
SO, (b) (d)
