Statues and monuments in India are affected by acid rain. How?
Acid rain is caused by various human activities that leads to the emission of oxides of Sulphur and nitrogen in the atmosphere. These oxides undergo oxidation and then react with water vapour to form acids.
2SO2 (g) + O2 (g) + 2H2O (l) → 2H2SO4 (aq)
4NO2 (g) + O2 (g) + 2H2O (l) → 4HNO3 (aq)
Acid rain causes damage to buildings and structures made of stone and metal. In India, limestone is a major stone used in the construction of various monuments and statues, including the Taj Mahal.
Acid rain reacts with limestone as:
CaCO3 + H2SO4 → CaSO4 + H2O + CO2
Thus resulting in the loss of luster and colour of monuments, leading to their disintegration.
Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?
What are the harmful effects of photochemical smog and how can they be controlled?
Write down the reactions involved during the formation of photochemical smog.
Explain tropospheric pollution in 100 words.
What are the reactions involved for ozone layer depletion in the stratosphere?
What would have happened if the greenhouse gases were totally missing in the earth's atmosphere? Discuss.
What do you mean by green chemistry? How will it help decrease environmental pollution?
What is smog? How is classical smog different from photochemical smog?
What do you mean by ozone hole? What are its consequences?
A large number of fish are suddenly found floating dead on a lake. There is no evidence of toxic dumping but you find an abundance of phytoplankton. Suggest a reason for the fish kill.
How do you account for the formation of ethane during chlorination of methane?
What are hybridisation states of each carbon atom in the following compounds ?
(i) CH2=C=O,
(ii) CH3CH=CH2,
(iii) (CH3)2CO,
(iv) CH2=CHCN,
(v) C6H6
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
What are the common physical and chemical features of alkali metals?
Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4
Assign oxidation number to the underlined elements in each of the following species:
(a) NaH2PO4
(b) NaHSO4
(c) H4P2O7
(d) K2MnO4
(e) CaO2
(f) NaBH4
(g) H2S2O7
(h) KAl(SO4)2.12 H2O
What is the basic theme of organisation in the periodic table?
Explain the formation of a chemical bond.
Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.
A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?
On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
Give reasons:
(i) Conc. HNO3 can be transported in aluminium container.
(ii) A mixture of dilute NaOH and aluminium pieces is used to open drain.
(iii) Graphite is used as lubricant.
(iv) Diamond is used as an abrasive.
(v) Aluminium alloys are used to make aircraft body.
(vi) Aluminium utensils should not be kept in water overnight.
(vii) Aluminium wire is used to make transmission cables.
Discuss the chemistry of Lassaigne's test.
Which one of the following statements is incorrect in relation to ionization enthalpy?
(a) Ionization enthalpy increases for each successive electron.
(b) The greatest increase in ionization enthalpy is experienced on removal of electron from core noble gas configuration.
(c) End of valence electrons is marked by a big jump in ionization enthalpy.
(d) Removal of electron from orbitals bearing lower n value is easier than from orbital having higher n value.
How many neutrons and protons are there in the following nuclei?
Calculate the wave number for the longest wavelength transition in the Balmer series of atomic hydrogen.
Round up the following upto three significant figures:
(i) 34.216
(ii) 10.4107
(iii) 0.04597
(iv) 2808
Write Lewis dot symbols for atoms of the following elements: Mg, Na, B, O, N, Br.
Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?
In the organic compound CH2 = CH – CH2 – CH2 – C ≡ CH, the pair of hydridised orbitals involved in the formation of: C2 – C3 bond is:
(a) sp – sp2
(b) sp – sp3
(c) sp2 – sp3
(d) sp3 – sp3