The intermixing of particles of two different types of matter on their own is called
- A.Osmosis
- B.Brownian motion
- C.Diffusion
- D.Conductance
Correct answer
Explanation
The correct answer is C, Diffusion. Diffusion is the spontaneous mixing of the particles of two substances, caused by the constant motion of those particles.
Particles of matter are always moving and have spaces between them. So when two substances meet, their particles spread into each other's gaps without any stirring. The smell of incense filling a room, a drop of ink colouring a glass of water and the exchange of oxygen and carbon dioxide in our lungs are all examples. Diffusion is fastest in gases, slower in liquids and very slow in solids, and it speeds up as the temperature rises because the particles move faster.
A is wrong: osmosis is the movement of solvent, usually water, through a semi-permeable membrane from a dilute to a concentrated solution.
B is wrong: Brownian motion is the random zigzag movement of tiny particles suspended in a fluid; it is evidence for moving molecules, not the mixing itself.
D is wrong: conductance measures how easily electric current flows through a conductor.
Exam tip: diffusion needs no membrane; osmosis is a special case of solvent movement through a semi-permeable membrane.
Practice Questions
View allConsider the following statements :
Statement-I : Giant stars live much longer than dwarf stars.
Statement-II : Compared to dwarf stars, giant stars have a greater rate of nuclear reactions.
Which one of the following is correct in respect of the above statements?
- A.Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
- B.Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
- C.Statement-I is correct, but Statement-II is incorrect
- D.Statement-I is incorrect, but Statement-II is correct
Show answer
Massive giant stars burn their fuel so fast that they live much shorter lives than dwarf stars, so Statement I is false and Statement II is true.
Read the full explanation →Which one of the following is a filter feeder?
- A.Catfish
- B.Octopus
- C.Oyster
- D.Pelican
Show answer
The oyster feeds by drawing water over its gills and straining out plankton and organic particles, which is filter feeding.
Read the full explanation →With reference to radioisotope thermoelectric generators (RTGs), consider the following statements :
1. RTGs are miniature fission reactors.
2. RTGs are used for powering the onboard systems of spacecrafts.
3. RTGs can use Plutonium-238, which is a by-product of weapons development.
Which of the statements given above are correct ?
- A.1 and 2 only
- B.2 and 3 only
- C.1 and 3 only
- D.1, 2 and 3
Show answer
RTGs power spacecraft using heat from the natural decay of plutonium-238; they are not reactors and involve no fission. In an RTG, a radioactive isotope gives off heat as it decays on its own.
Read the full explanation →Consider the following :
1. Cashew
2. Papaya
3. Red sanders
How many of the above trees are actually native to India ?
- A.Only one
- B.Only two
- C.All three
- D.None
Show answer
Of the three, only red sanders is native to India; cashew and papaya were brought from the Americas. Red sanders (Pterocarpus santalinus) is endemic to the southern Eastern Ghats, mainly the Seshachalam and nearby hills of Andhra Pradesh.
Read the full explanation →Consider the following :
1. Butterflies
2. Fish
3. Frogs
How many of the above have poisonous species among them ?
- A.Only one
- B.Only two
- C.All three
- D.None
Show answer
Each of the three groups includes species that carry toxins in their bodies to deter predators. Butterflies: the Monarch butterfly feeds as a caterpillar on milkweed and stores its bitter cardiac glycosides, so birds that eat it fall sick; its bright orange colour is a warning.
Read the full explanation →