1 Atomic Structure
A boy weighing 20 Kg is running with a speed of 18 km/hr18 km/hr. What is his de-Broglie wavelength? 1) 6.626×10−34 2) 6.626×10−36 3) 3.626×10−34 4) 3.626×10−36
De broglie wavelength ($$\lambda$$) $$ = h/mv$$
2 Basic Principles of Organic Chemistry
Conversion of CH4 to CH3Cl is an example of ______ reaction .
1) nucleophilic substitution 2) electrophilic substitution 3) Free radical addition 4) Free radical substitution.
When methane gas is treated with chlorine in the presence by sunlight, one hydrogen of methane replaced by the chlorine atom and forms methyl chloride. The mechanism involved in this reaction is free radical mechanism. So it is an example of free radical substitution reaction.
3 Classification of Elements and Periodicity
The first ionization potential of four consecutive elements in the second period of the periodic table are 8.3, 11.3, 14.5 and 13.6 eV respectively. Which one of the following is the first ionization potential of carbon? 1) 13.6 2) 11.3 3) 8.3 4) 14.5
SOLUTION
The first ionization potential of carbon is 11.3 V The four consecutive elements are B,C,N and O. We know that the first ionization potential of N is higher than the first ionization potential of O as in case of N, the electron is to be removed from stable half-filled 2p orbital.
4 Solutions
The number of sodium atoms in 2 moles of sodium ferrocyanide is
1) 8 x 6.02 x 1023
2) 4 x 6.02 x 1023
3) 6.02 x 1023
4) 2
Formul of sodium ferrocyanide Na4?[Fe(CN)6?] of suggest that it has four sodium atoms.
Number of Na atoms= Number of moles × number of atoms per molecule × Avogadro number
=2×4×6.023×1023
=48×1023
5 D and F Block Elements
Aqueous solution of a metallic nitrate X reacts with NH4OH to form Y which dissolves in excess NH4OH. The resulting complex is reduced by acetaldehyde to deposit the metal. X and Y, respectively, are:
1) Cs(NO3) and CsOH 2) Zn(NO3)2 and ZnO 3) AgNO3 and Ag2O 4) Mg(NO3) and Mg(OH)2
6 Hydrocarbons
In benzene, all the six C-C bonds have the same length because of :
1) Isomerism 2) chain isomerism 3) resonance 4) hybridisation.
7 Electrochemistry
The ratio of weights of hydrogen and magnesium deposited by the same amount of electricity from aqueous H2SO4 and fused MgSO4 are: 1) 1:8 2) 1:12 3) 1:16 4) 1:1
SOLUTION Acc. to Faraday 2nd Law of electrolysis.
w1 / w2=E1 /E2 w1= At deposited of element H. w1 / w2=1 / 12 w2 = At deposited of element Mg.
8 S – Block Elements
A substance X is a compound of an element of group IA. The substance X gives a violet colour in flame test. X is
1) NaCl
2) KCl
3) LiCl
4) None
Solution
Since potassium gives violet colour on the flame test, the substance X is KCl.
9 Chemical Kinetics
A catalyst in the finely divided state is more efficient because in this state
1) it can react with one of the reactant more efficiently
2) it has larger activation energy
3) it has large surface area
4) all of the above
10 P – Block Elements
Which atom contains exactly 15 protons? 1. P-32 2. S-32 3. O-15 4. N-15
An atom with 15 protons also has an atomic number of 15. Refer to the Periodic Table for element 15 (phosphorus).
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