Tag: evs

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Questions Related to evs

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

If a boiled and filtered hard water is added to soap and it lathers, the water is :

  1. temporary hard water

  2. permanent hard water

  3. both a and b

  4. data insufficient
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hardness of water can be of two types temporary and permanent hardness. Temporary hard water contains only bicarbonates of magnesium and calcium. It can be removed by boiling. Such water on treating with soap lathers easily.

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

Types of hardness of water is :

  1. temporary and semi-permanent

  2. permanent and temporary

  3. permanent and partially permanent

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hardness of water can be of two types temporary and permanent hardness. Temporary hard water contains only bicarbonates of magnesium and calcium. It can be removed by boiling. Permanent hard water contains chlorides and sulfates of calcium and magnesium. It can be removed by adding washing soda.

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

What is the advantage of using detergents over soap in hard water?

  1. can be used with both hard and soft water

  2. used in acidic solutions

  3. prepared from hydrocarbons of petroleum

  4. all of above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Soaps are not suitable when hard water is used. Detergents can be used with both hard and soft water. Detergents are more soluble in water than soaps. They also have a stronger cleansing action than soaps. Detergents don't need expensive vegetable oil for their preparation as they can be prepared from hydrocarbons of petroleum. They can be used in acidic solutions whereas soaps cannot be used (free fatty acids are precipitated).

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

The given sample of lathers easily with water, it is :

  1. hard water.

  2. soft water.

  3. permanent hard water.

  4. temporary hard water.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Soft water is surface water that contains low concentrations of ions and in particular is low in ions of calcium and magnesium. Because soft water has few calcium ions, there is no inhibition of the action of soaps and no soap scum is formed in normal washing. It lathers easily with water. Similarly, soft water produces no calcium deposits in water heating systems.

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

A cloudy or milky appearance characterizes :

  1. soft water

  2. hard water

  3. chlorinated water

  4. both a and c
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An easy way in which water manifests its hardness is scaling i.e. forming deposits through calcification that clog plumbing. These scales are usually white because calcium and magnesium are the most common sources of hardness in water. In swimming pools, a cloudy or milky appearance characterizes hard water.

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

A soap is :

  1. sodium or potassium salt of organic acid

  2. sodium salts of sulphonic acid

  3. both a and b

  4. chloride salts of organic and sulphonic acid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Soap is the sodium and potassium salt of organic fatty acid. Soap reacts with hard water forming scum. They are derived from the treatment of tryglycerides with a strong base (saponification). Soaps are made by rendering fats from animal sources.

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

Sodium salts of sulphonic acid are :

  1. soap

  2. detergents

  3. hard water

  4. soft water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Detergents are soap-like compounds which are used for cleaning purpose. They are sodium salts of long chain alkyl benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphate, whereas, soaps are sodium salts of long chain carboxylic acids.

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

Washing soda soften both temporal and permanent hardness by :

  1. Dissolving salts

  2. Forming precipitate

  3. Forming soluble salts

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Permanent hard water can be made soft by adding sodium carbonate (also called washing soda) to it. This will soften both temporal and permanent hardness. In this chemical reaction, the calcium and magnesium ions react with sodium to form a precipitate.