1. Reaction in which heat is released.
2. Reaction in which heat is absorbed.
3. Reaction in which neither heat is released nor absorbed.
4. None of these
Option “B” is correct The term endothermic process describes a process or reaction in which the system absorbs energy in the form of heat.
282. Manganite is an ore/mineral of –
1. Beryllium
2. Chromium
3. Manganese
4. Copper
Option “C” is correct Manganite is an ore of Manganese.
283. Pentane has _____ structural isomers.
1. 1
2. 2
3. 3
4. 4
Option “C” is correct Pentane (C5H12) has three structural isomers.
284. Sphalerite is an ore/mineral of –
1. Mercury
2. Molybdenum
3. Silver
4. Zinc
Option “D” is correct Sphalerite is the chief ore of Zinc.
285. Why do atoms bond?
1. To reduce potential energy and gain stability
2. To make atoms
3. To increase potential energy and lose stability
4. To increase potential energy and gain stability
Option “A” is correct Atoms bond with each other to reduce potential energy and gain stability.
286. Which of the following is present in Nail polish remover?
1. Citric acid
2. Acetone
3. Ethylene
4. Benzene
Option “B” is correct Acetone is a colorless, flammable liquid that evaporates easily.In cosmetics, the most common use of acetone is in nail polish remover.
Option “C” is correct Redox reaction is the reaction in which oxidation and reduction occurs simultaneously. Rust of iron is nothing but hydrate of iron oxide and iron (III) oxide -hydroxide.
288. Which of the following is an ore of Aluminum?
1. Galena
2. Cryollite
3. Cinnabar
4. Epsom Salt
Option “B” is correct Cryollite is an ore of aluminium, Galena is an ore of lead, Cinnabar is an ore of mercury and Epsom Salt is an ore of magnesium.
289. Process of gaining electrons is known as _____.
1. Oxidation
2. Reduction
3. Radiation
4. Both oxidation and reduction
Option “B” is correct :Reduction is the loss of oxygen from a molecule or the gaining of one or more electrons.
290. Which of the following metal (shown by its symbol) is generally used for making filaments of bulb?
1. Fe
2. An
3. Ag
4. W
Option “D” is correct Most incandescent bulbs use tungsten (W) as a filament element. Tungsten is an inexpensive metal that has a long lifespan as a filament. It is a suitable option for incandescent bulbs because it has an extremely high melting point and is flexible. Pliable tungsten filaments are easily formed and hold up well against temperatures as high as 4,500 degrees Fahrenheit.
