User Forum

Preeti has collected some items from her kitchen :
i. Amla
ii. Baking soda
iii. Tamarind
iv. Soap
v. Lime water
vi.Common salt
vii.Sugar
She classified them as acidic, basic and neutral substances.
Which of the following classification is correct?

          Acidic              Basic                Neutral
A(i), (ii)            (iv), (vii)            (iii), (v), (vi)
B(iv), (vi)         (i), (ii), (iii)          (v), (vii)
C(i), (iii)          (ii), (v), (vi)          (iv), (vii)
D(i), (iii)          (ii), (iv), (v)          (vi), (vii)

Select the option that will correctly complete the word given in bold in the following statement.
We need to wear W_ _ L _ E _ clothes when temperature is low.

AOULN
BOOEN
COOLN
DOOLY

Which of the following products is made from the softest mineral?

A
B
C
D

There are two walls A and B which are 180 m apart from each other. A boy standing at 60 m away from wall A claps his hands once. If the speed of sound in air is 330 m s^-1, what is the time interval between the first and the second echo that he hears?

A 0.36 s
B 0.24 s
C 0.4 s
D 1 s

The diagram shows the positions of the air particles due to propagation of sound, represented by straight lines, at a particular instant from P to Q.

Which of the following statements correctly depicts the pressure variation with respect to distance?

A The lines which are closed to one another represent rarefaction which is a low pressure region.
B The lines which are far apart from one another represent compression which is a low pressure region.
C The lines which are far apart from one another represent rarefaction which is high pressure region.
D The lines which are closed to one another represent compression which is a high pressure region.

The frequency of a source is 20 kHz. The frequencies of the sound waves produced by it in water and air will

A Be the same as that of the source
B Depend upon the velocity of the waves in these media
C Depend upon the wavelength of the waves in these media
D Depend upon the density of the media.

Which of the following is a correct match?

Select an INCORRECT pair.

Rashi had to make four pairs each having one wild and one domestic animal but she made mistake while making one of the pairs. Select the INCORRECT pair.
A Zebra, Dog
B Leopard, Sheep
C Cow, Horse
D Whale, Goat

Choose the correct option for the given statements.

I. Plastics are generally good conductors of electricity.
II. Ropes made by bakelite are used in cranes and elevators.
III. Teflon is a special plastic on which oil and water do not stick.
IV. Plastic is non-biodegradable, hence not environment friendly.