The smog is essentially caused by the presence of

• O₂ and O₃

• O₃ and N₂

• Oxides of sulphur and nitrogen

• Oxides of sulphur and nitrogen

The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ion is required to make teeth enamel harder by converting [3Ca₃ (PO4)2.Ca(OH)_2] to

• [3{Ca(OH)₂}. CaF₂]

• [CaF₂]

• [3(CaF₂). Ca(OH)₂]

• [3Ca₃(PO₄)₂. CaF₂]

Among the following, the one which is not a "green house gas", is

• N₂O

• CO₂

• CH₄

• O₂

Metal ion responsible for the Minimata disease is

• Co²⁺

• Hg²⁺

• Cu²⁺

• Zn²⁺

105.

The ozone layer forms naturally by

• the interaction of CFC with oxygen

• the interaction of UV radiation with oxygen

• the interaction of IR radiation with oxygen

• the interaction of oxygen and water vapour

The chemical entities present in thermosphere of the atmosphere are

• ${\mathrm{O}}_2^{+}, {\mathrm{O}}^{+}, {\mathrm{NO}}^{+}$

• O₃

• ${\mathrm{N}}_2, {\mathrm{O}}_2, {\mathrm{CO}}_2, {\mathrm{H}}_2\mathrm{O}$

• ${\mathrm{O}}_3, {\mathrm{O}}_2^{+}, {\mathrm{O}}_2$

Match the following and choose the correct option given below:-

Compound / Type	Use
A. Dry ice	I. Anti-knocking compound
B. Semiconductor	II. Electronic diode or triode
C. Solder	III. Joining circuits
D. TEL	IV. Refrigerant for preserving food

• A - I; B - II; C - IV; D - III

• A - II; B - III; C - I ; D - IV

• A - IV; B - III; C - II; D - I

• A - IV; B - II; C - III; D - I

An odd electron molecule among the following is

• CO

• SO₂

• CO₂

• NO

Green chemistry deals with

• study of plant physiology

• study of extraction of natural products from plants

• detailed study of reactions involved in the synthesis of chlorophyll

• utilization of existing knowledge base for reducing the chemical hazards along with developmental activities

A sample of sea water contains 5 × 10^-3 g of dissolved oxygen in 1 kg of the sample. The concentration of O₂ in that sea water sample in ppm is

• 5

• 5 × 10^-3

• 5 × 10^-2

• 5 × 10^-1