Consider the following statements : I. A colloid and a suspension are heterogeneous mixtures. II. Colloids can be separated from the mixture by the process of centrifugation. III. Particles of colloids and suspensions can be seen by naked eye. IV. The aqueous solution of copper sulphate does not show Tyndall effect; however, the mixture of milk and water shows Tyndall effect. Which of the statements given above is/are correct?
- A.I only
- B.II and III only
- C.I, II and III
- D.I, II and IV
Correct answer
Explanation
The correct answer is D, I, II and IV. Only statement III is wrong, because colloidal particles are too small to be seen with the naked eye.
Mixtures are graded by particle size. A true solution has particles below about 1 nm, a colloid between 1 and 1000 nm, and a suspension above that. Colloids and suspensions are both heterogeneous, which is statement I. Colloidal particles do not settle on standing and pass through filter paper, but spinning at high speed in a centrifuge forces them out, as when cream is separated from milk, which is statement II. Colloidal particles scatter a beam of light and make its path visible, the Tyndall effect, so diluted milk shows it while copper sulphate solution, a true solution, does not, which is statement IV.
A, I only, leaves out the correct statements II and IV.
B, II and III only, includes the wrong statement III and leaves out I and IV.
C, I, II and III, wrongly includes III and leaves out IV.
Exam tip: solution below 1 nm, colloid 1 to 1000 nm, suspension larger; only colloids and suspensions show the Tyndall effect.
Practice Questions
View allConsider the following actions :
1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously
2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive
3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode
In how many of the above actions is the function of accelerometer required?
- A.Only one
- B.Only two
- C.All three
- D.None
Show answer
An accelerometer measures acceleration, including the pull of gravity, and each of the three actions depends on reading it. An accelerometer is a small sensor, today usually a MEMS (micro-electro-mechanical system) chip, that senses changes in speed and the direction of gravity.
Read the full explanation →Consider the following statements :
1. Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.
2. Carbon fibres once used cannot be recycled.
Which of the statements given above is/are correct?
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
Show answer
Carbon fibre is widely used in cars and aircraft for its strength and low weight, and it can be recovered and recycled.
Read the full explanation →Which one of the following cell organelles contains DNA?
- A.Golgi apparatus
- B.Mitochondrion
- C.Lysosome
- D.Endoplasmic reticulum
Show answer
Mitochondria carry their own small, circular DNA and their own ribosomes. Mitochondria are the powerhouses of the cell, where aerobic respiration makes ATP.
Read the full explanation →Which set of vegetables is underground stem or modified stem of a plant?
- A.Potato, artichoke, round gourd
- B.Onion, garlic, carrot
- C.Potato, onion, garlic
- D.Potato, garlic, turnip
Show answer
All three are underground modified stems: the potato is a stem tuber, and onion and garlic are bulbs. A stem can be told from a root by its nodes and buds.
Read the full explanation →A sound wave having frequency of 300 Hz is travelling in an unknown medium. Its wavelength is not known. It travels a distance equal to 150 times its wavelength in time t. The value of t is :
- A.0.5 s
- B.1 s
- C.1.5 s
- D.2 s
Show answer
A wave moves forward by one wavelength in each cycle, so 150 wavelengths take 150 cycles, and 150 cycles at 300 per second take half a second.
Read the full explanation →