21.

For which colour of light the focal length of a lens will be maximum?

• Violet

• Blue

• Red

• Yellow

100 Newton force is applied perpendicularly on the surface of 10 cm, the pressure on that surface will be

• 1x10⁵ Newton/m²

• 10x10⁵ Newton/m²

• 1x10^-5 Newton/m²

• 10⁶ Newton/m²

If the kinetic energy of a body is increased by 0.1%, then an increase in its momentum will be

• 0.05%

• 0.1 %

• 1.0%

• 10%

How will you find creative students in a class?

• By giving mathematical question

• By asking them to read a paragraph from a book

• By asking them to tell new usage of an object

• By asking them to memorize a big chemical formula

The speed of sound in air at NTP is 332 m/s. If air pressure becomes four times, then the speed of sound will be

• 166 m/s

• 332 m/s

• 664 m/s

• 1328 m/s

Each of the five capacitors shown in the given bridge circuit is 10 µF connected with a 100V DC source. The equivalent capacitance between the points A and B is

• 40 µF

• 30 µF

• 20 µF

• 10 µF

Name the process used for purification of white bauxite ore containing no iron oxide as an impurity.

• Bayer's process

• Hall's process

• Serpek's process

• Hoopes electrolytic process

Name an acid used for removing ink stains

• Oxalic acid

• Acetic acid

• Formic acid

• Malic acid

A force $\mathrm{F} = (5\stackrel{\wedge }{\mathrm{i}} + 3\stackrel{\wedge }{\mathrm{j}})$ Newton displaces a body by $(2\stackrel{\wedge }{\mathrm{i}}- \stackrel{\wedge }{\mathrm{j}})$. The work done is

• zero

• 7 J

• 12 J

• 13 J

The temperature at which ferromagnetism vanishes and the substance becomes paramagnetic is called

• Inversion temperature

• Boyle temperature

• Curie temperature

• Kelvin temperature