Is Matter Around Us Pure - Class 9 MCQ

In its normal stable state, blood is a suspension, which is a colloid. It mainly consists of red & white blood cells, and lymphocytes suspended in plasma. When acted upon by external forces, such as a centrifuge found in hospitals, the blood separates into its constituents just as a suspension does

Explanation:
Molten brass is a solution of copper in molten zinc. Here's a detailed explanation:
Definition of Brass:
- Brass is an alloy made primarily of copper and zinc.
- It is often used in applications where low friction is required, such as musical instruments, plumbing fittings, and electrical connectors.
Molten Brass:
- When brass is in a molten state, it means that it has been heated to a high temperature and has melted.
- In this state, the copper and zinc atoms are mixed together, forming a homogeneous solution.
Molten Copper in Brass:
- In molten brass, the copper atoms are dissolved in the molten zinc.
- This means that the copper atoms are evenly distributed throughout the molten zinc, forming a solution.
- The concentration of copper in the molten brass can vary depending on the desired properties of the alloy.
Choice D: Molten Zinc:
- The correct answer is choice D, as molten brass is a solution of molten copper in molten zinc.
- The molten zinc acts as the solvent, while the molten copper is the solute.
Other Choices:
- Choice A: Solid Zinc - Solid zinc is not involved in the formation of molten brass. Brass is formed by melting copper and zinc together, not by dissolving copper in solid zinc.
- Choice B: Molten Tin - Molten tin is not involved in the formation of molten brass. Brass is formed by melting copper and zinc together, not by dissolving copper in molten tin.
- Choice C: Gaseous Zinc - Gaseous zinc is not involved in the formation of molten brass. Brass is formed by melting copper and zinc together, not by dissolving copper in gaseous zinc.
Therefore, the correct answer is choice D: Molten Zinc.

To determine the weight of 24 carats of a diamond, we need to convert carats to milligrams (mg).
- 1 carat is equal to 200 milligrams (mg).
- Therefore, 24 carats is equal to 24 * 200 = 4800 milligrams (mg).
Now, we can compare this weight to the given options:
A: 95% mg - This option does not make sense as it is not a unit of weight.
B: 200 mg - This option is incorrect because 24 carats is equal to 4800 mg, not 200 mg.
C: 100 g - This option is incorrect because it is a unit of weight in grams, not milligrams.
D: 100 mg - This option is incorrect because 24 carats is equal to 4800 mg, not 100 mg.
Therefore, the correct answer is option B: 200 mg.

Nanometer is a unit for measuring micro-distance.
Explanation:
- Nanometer is a metric unit of length in the International System of Units (SI).
- It is denoted by the symbol "nm" and is equal to one billionth of a meter.
- The prefix "nano" means one billionth.
- Nanometer is commonly used to measure extremely small distances, especially on the scale of atoms and molecules.
- It is often used in fields such as nanotechnology, physics, chemistry, and biology.
- Nanometer is smaller than both millimeter and micrometer.
- 1 nanometer is equal to 0.001 micrometers or 0.000001 millimeters.
- Some examples of objects that can be measured in nanometers include the width of a human hair, the size of nanoparticles, and the wavelength of visible light.
In conclusion, nanometer is a unit specifically used to measure micro-distance and is commonly used in various scientific and technological fields.

To determine the solute and solvent in a sugar solution, we need to understand the definitions of solute and solvent.
Solute: A solute is the substance that is dissolved in a solution.
Solvent: A solvent is the substance in which the solute is dissolved.
In the case of a sugar solution, the solute is sugar and the solvent is water. This means that:
- Sugar is the solute. Sugar is the substance that is being dissolved in the solution.
- Water is the solvent. Water is the substance in which the sugar is being dissolved.
Hence, the correct answer is option B: Sugar is solute, water is solvent.