Ques 1:
Why does the rainwater normally have a pH of about 5.6? When does it become acid rain?
Ques 2:
A compound C7 H14 on ozonolysis gives ethanal and pentan–3- one. What is the structure of alkene?
Ques 3:
A metal ‘X’ is present in chlorophyll. Identify the metal ‘X’. How does this metal react with N2?
Ques 4:
An element ‘A’ belongs to group 2 of the periodic table. It shows anomalous behaviour from the rest of the elements of its group. It shows a diagonal relationship with another element ‘B’. Chlorides of both ‘A’ and ‘B’ have bridged structure in vapour phase. Identify A and B and draw the structures of their respective chlorides.
Ques 5:
Consider the reaction of water with F2 and suggest, in terms of oxidation and reduction, which species are oxidized/ reduced.
Ques 6:
Critical temperature of ammonia and carbon dioxide are 405.5 K and 304.10 K respectively. Which these gases will liquefy first when you start cooling from 500K to their critical temperature
Ques 7:
The drain cleaner contains small bits of aluminium which react with caustic soda to produce dihydrogen gas. What volume of dihydrogen at 20°C and one CBSE Board Class XI Chemistry bar pressure will be released when 0.15 g of aluminium reacts
Ques 8:
(a) Write the atomic number of the element present in the third period and seventeenth group of the periodic table.
(b) Out of the elements Cr (Z = 24), Mg (Z=12) and Fe (Z =26), identify the element with five electrons in 3d subshell.
Ques 9:
Which of the following statements related to the modern periodic table is incorrect and why?
(a) Each block contains a number of columns equal to the number of electrons that can occupy that subshell.
(b) The d – block has 8 columns, because a maximum 8 electrons can occupy all the orbitals in d – sub shell.
Ques 10:
Among the elements B, Al, C and Si:
(a) Which has the highest first ionization enthalpy?
(b) Which has the most negative electron gain enthalpy? Give reason
Ques 11:
What is shielding effect? How it affects atomic size in lanthanides?
Ques 12:
Find the number of moles of 4.9g of sulphuric acid?
Ques 13:
Show how hyperconjugation occurs in propene molecule
Ques 14:
How can you explain the formation of NaCl according to Kossel concept?
Ques 15:
What is a black body? What are the characteristics of black body radiation?
Ques 16:
Why is Ga smaller in size than Al?
Ques 17:
Express 32.392800 to four significant figures
Ques 18:
If a tank is full of water coming in and out at the same rate, then what will happen to the level of water in a tank?
Ques 19:
Why the bottle containing hydrogen peroxide should be cooled before opening?
Ques 20:
Why the symbols of \(_{35}^{79}\textrm{Br}\)
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