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Questions Related to evs

Car wax is prepared from

evs eat when you need food poisoning and food preservation methods food spoilage, adulteration and preservation food spoilage and adulteration

  1. Vegetable wax

  2. Animal wax

  3. Mineral wax

  4. All of the above

Show answer
Correct Option: A
Explanation:

A traditional car wax formula usually consists of a blend of carnauba wax, mixed with other waxes, such as beeswax, natural oils, and will sometimes also include petroleum distillates. Carnauba wax is a hard wax obtained from the leaves of a Brazilian palm tree which produces a glassy shine. Carnauba based waxes must be reapplied frequently in order to maintain shine. Beeswax is a durable wax found in honeycombs and used in car wax formulas to provide a protective barrier. Natural oils, such as linseed oil, are emollients use to provide added shine, luster, and protection, to the painted surface. Petroleum distillates are solvents derived from crude oil that make the wax easier to spread and to clean the paint.

So, the correct answer is option D.

Apples coated with carbomethylchitosan remains fresh for

evs eat when you need food poisoning and food preservation methods food spoilage, adulteration and preservation food spoilage and adulteration

  1. $1\ month$

  2. $6\ months$

  3. $1\ year$

  4. $1\ year$ and $6\ months$

Show answer
Correct Option: B
Explanation:

Carbonmethylchitosan is the wax-like structure present on the apples like a coating structure. This wax coating is very important in apples because this coating maintains the freshness of apple for a long time is near about 6 to 8 months. This type of chitosan is made by treating the chitin shells and shrimps of other crustaceans with an alkaline substance like sodium hydroxide.
So, the correct option is '6 months'.

Pollen grains can be stored in a viable condition for many years in which of the following conditions?

evs eat when you need food poisoning and food preservation methods food spoilage, adulteration and preservation food spoilage and adulteration

  1. Anaerobic conditions in 0$^o$ C

  2. Liquid nitrogen (-196$^o$ C)

  3. Liquid nitrogen (0$^o$ C)

  4. Liquid hydrogen (196$^o$ C)

Show answer
Correct Option: B
Explanation:
Pollen grains are stored for many years in the liquid nitrogen, having the temperature of -196 degrees of Celsius. This method of saving is called cryopreservation. The low temperature allows storing for a longer period as it reduces the growth rate of cells. The cryoprotective agents delay the aging of the plants and protect the plants from the damages due to cold.
So, the correct answer is 'Liquid nitrogen (-196$^o$ C)'.

A sample of water which freely lathers with soap solution is called hard water.

evs experiments with water water and its types hard and soft water what floats - what sinks

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

In hard water, lather is very difficult to form, leather is not formed in hard water.

A sample of water which starts lathering with soap solution on boiling is called temporary hard water.

evs experiments with water water and its types hard and soft water what floats - what sinks

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

A temporary hard water can from lather with soap. The ${ Ca }^{ 2+ }/{ Mg }^{ 2+ }$ ions of water displace ${ Na }^{ + }$ or ${ K }^{ + }$ ions from this salts & form insoluble $Ca/Mg$ salts of fatty acids. 

$\because $ it is temporary hard water, lathering of soap is not that difficult.

Which of the following has a low calcium and magnesium content?

evs experiments with water water and its types hard and soft water what floats - what sinks

  1. Soft water

  2. Hard water

  3. Contaminated water

  4. None of the above

Show answer
Correct Option: A
Explanation:

Soft water is surface water that contains low  concentrations of ions and in particular is low in ions of calcium and magnesium. Soft water naturally occurs where rainfall and the drainage basin of rivers are formed of hard, impervious and calcium poor rocks.

What is hard water?

evs experiments with water water and its types hard and soft water what floats - what sinks

  1. Low mineral content

  2. Contaminated water

  3. High mineral content

  4. Both B and C

Show answer
Correct Option: D
Explanation:

Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone and chalk which are largely made up of calcium and magnesium carbonates. Hard drinking water may have moderate health benefits, but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling towers, and other equipment that handles water.

Permanent hardness can be removed by simple boiling it.

evs experiments with water water and its types hard and soft water what floats - what sinks

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Permanent hardness is caused by the presence of sulfates of $Ca/Mg$. Which further increases the hardness on boiling because boiling removes only water in the form of vapour while none of its mineral content boil away-they remain in the vessel.

.................. water does not lather with soap

evs experiments with water water and its types hard and soft water what floats - what sinks

  1. Hard water

  2. Soft water

  3. Contaminated water

  4. None of the above

Show answer
Correct Option: A
Explanation:

Hard water does not lather with but instead forms a gooey mass called scum. Hard water is formed when water percolates through deposits of limestone and chalk which are largely made up of calcium and magnesium carbonates.

Boiling hard water with washing soda removes permanent hardness.

evs experiments with water water and its types hard and soft water what floats - what sinks

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Boiling hard water with washing soda removes permanent hardness which removes ${ Ca }^{ 2+ }$ or ${ Mg }^{ 2+ }$ ions in a precipitation reaction.