Chemistry - Study Mode

[#891] The green colour seen in firework displays is due to the chloride salt of :
Correct Answer

(C) Barium

Explanation

Solution: The red, orange, yellow, green, blue and purple colors exploding in the night sky during a pyrotechnic festival are created by the use of metal salts. Barium chloride provides green colour to firework displays. Metal salts that are commonly used in firework displays include: strontium carbonate (red), calcium chloride (orange), sodium nitrate (yellow), barium chloride (green fireworks) and copper chloride (blue fireworks).

[#892] In deep-sea diving, divers use a mixture of gases consisting of oxygen and
Correct Answer

(D) Helium

Explanation

Solution: Question: Deep-sea divers breathe a special mix of gases to stay safe underwater. Oxygen is part of the mix, but what other gas is commonly added? Explanation: Divers need to breathe underwater, just like we do on land. Oxygen is essential for life, but breathing pure oxygen at high pressure (like deep underwater) can be dangerous. That's why another gas is added to dilute the oxygen. Helium is the most common choice because it is: 1. Lightweight: This makes it easier to breathe at depth. 2. Inert: It doesn't react with the body or other gases. 3. Safe at high pressure: Unlike some other gases, helium doesn't cause problems when breathed under pressure at great depths. Therefore, the correct answer is D: Helium.

[#893] Now-a-days yellow lamps are frequently used as street lights. Which of the following gases is used in these lamps ?
Correct Answer

(A) Sodium

Explanation

Solution: A sodium-vapour lamp is a gas-discharge lamp that uses sodium in an excited state to produce light. There are two varieties of such lamps: low pressure and high pressure. Low-pressure sodium lamps are the most efficient electrical light sources, but their yellow light restricts applications to outdoor lighting such as street lamps. High-pressure sodium lamps have a broader spectrum of light but poorer colour rendering than other types. Because sodium vapour lamps cause less light pollution than mercury-vapour lamps, many cities that have large astronomical observatories employ them.

[#894] Which of the following is not soluble in water ?
Correct Answer

(B) Zinc sulphate

Explanation

Solution: Zinc sulphate is not soluble in water.

[#895] The most volatile of the given liquids is
Correct Answer

(D) Liquid He

Explanation

Solution: Liquid Helium is the most volatile liquid.