1. F, K, Cl, I
Ans: K
K is placed in group 1 while others are placed in group 17 of the modem periodic table.
2. Lithium, Sodium, Magnesium, Potassium
Ans: Magnesium
Magnesium is an alkaline earth metal while others are alkali metals.
3. Beryllium, Helium, Neon, Argon
Ans: Beryllium
Beryllium is an alkaline earth metal while others are noble gases.
4. Gallium, Scandium, Germanium, Calcium
Ans: Germanium
Germanium is a metalloid while others are metals.
5. Boron, Arsenic, Germanium, Gallium
Ans: Gallium
Gallium is a metal while others are metalloids.
6. Dobereiner, Newland, Mendeleev, Moseley
Ans: Moseley
Moseley arranged elements in an increasing order of their atomic numbers whereas others arranged elements based on their atomic masses.
7. Fluorine, Boron, Bromine, Chlorine
Ans: Boron
Boron is placed in group 13 while others are placed in group 17 of the modem periodic table.
8. Carbon, Calcium, Oxygen, Neon
Ans: Calcium
Calcium is a s-block element while others are p-block elements.
9. Potassium, Magnesium, Calcium, Beryllium
Ans: Potassium
Potassium is placed in group 1 while others are placed in group 2 of the modern periodic table.
10. Beryllium, Magnesium, Carbon, Oxygen
Ans: Magnesium
Magnesium is placed in period 3 while others are placed in period 2 of the modem periodic table.
11. Voltmeter, Ammeter, Galvanometer, Electric motor
Ans: Electric motor
Electric motor is a device which converts electrical energy into mechanical energy whereas other devices are used to measure current and potential difference in a circuit.
12. Loud speaker, Magnet, Microphone, Electric motor
Ans: Magnet.
Others devices are based on the phenomenon of electromagnetism while magnet is not.
13. Fuse wire, Bad conductor, Rubber gloves, Generator
Ans: Generator.
Others restrict flow of current while generator is used to produce current.
14. Tungsten, Nichrome, Aluminium, Iron
Ans: Nichrome
Nichrome is an alloy used for making wires, while others are soft metals.
15. Boiler, Electric stove, Electric bulb, Electric bell
Ans: Electric bell
Others are used to generate heat energy whereas when it becomes hot whereas electric bell do not produce any heat energy.
16. Temperature, Conduction, Convection, Radiation
Ans: Temperature
Temperature is degree of hotness while conduction, convection and radiation are modes of heat transfer.
17. cal/g, cal/g °C, kcal/kg °C, erg/g °C
Ans: cal/g
cal/g is unit of specific latent heat while others are units of specific heat.
18. Joule, erg, Calorie, Newton
Ans: Newton
Newton is unit of force while others are units of heat energy.
19. Rainbow, Earthquake, Sunset, Sunrise
Ans: Earthquake
Others are due to different phenomenon of light whereas earthquake is a natural disaster.
20. Focal length, Radius of curvature, Image distance, Size of image
Ans: Size of image
All the other distances are measured from optical centre along the principal axis while size of image is measured perpendicular to the axis.
21. Simple microscope, Compound microscope, Telescope, Prism
Ans: Prism
Prism disperses light while other optical instruments produce magnified images of objects.
22. Eye lens, Retina, Cerebellum, Cornea
Ans: Cerebellum
Cerebellum is a part of brain while others are parts of eye.
23. Object distance, Image distance, Focal length, Principal axis
Ans: Principal axis
Except for principal axis, all other quantities can be measured physically with scale, thread, etc.
24. Eye piece, Magnifier, Kaleidoscope, Telescope
Ans: Kaleidoscope
Kaleidoscope uses mirrors while other devices make use of lenses.
25. Sodium, Potassium, Silver, Sulphur
Ans: Sulphur
Sulphur is a nonmetal while others are metals.
26. Boron, Chlorine, Bromine, Fluorine
Ans: Boron
Boron is placed in group 13 while others are placed in group 17 of the modern periodic table.
27. Copper, Iron, Mercury, Brass
Ans: Brass
Brass is a metalloid while others are metals.
28. Brass, Bronze, Phosphorous, Steel
Ans: Phosphorous
Phosphorus is a nonmetal while others are alloys.
29. Tinning, Alloying, Anodization, Froth floatation
Ans: Froth floatation
Froth floatation is a method used for the concentration of ores while others are methods used for prevention of corrosion.
30. Zinc coating, Tinning, Electroplating, Calcination
Ans: Calcination
Calcination is a process involved in extraction of carbonate ores while others arc methods used for prevention of corrosion.
31. Na, K, Cu, Li
Ans: Cu
Copper (Cu) is a less reactive metal while others are highly reactive metals.
32. Ethylene, Styrene, Propylene, Teflon
Ans: Teflon
Teflon is a polymer while others are monomer units of respective polymers.
33. Butane, Methane, Benzene, Ozone
Ans: Ozone
Ozone is inorganic while others are organic compounds.
34. CH4, C2H6, C5H12, CaCO3
Ans: CaCO3
Calcium carbonate (CaCO3) is an inorganic compound while others arc organic compounds.
35. C2H2, C3H8, C2H6, CH4
Ans: C2H2
Ethyne (C2H2) is a unsaturated hydrocarbon while others are saturated hydrocarbons.
36. C2H4, C4H10, C3H8, CH4
Ans: C2H4
Ethene (C2H4) is a unsaturated hydrocarbon while others are saturated hydrocarbons.
37. Sputnik, Moon, Swayam, Chandrayaan
Ans: Moon
Moon is a natural satellite whereas other are artificial satellite.