Why Should Curd and Sour Substances Not Be Kept in Brass and Copper Vessels? - Science


 Why should curd and sour substances not be kept in brass and copper vessels?


Solution 1

Curd and other sour substances contain acids. Therefore, when they are kept in brass and copper vessels, the metal reacts with the acid to liberate hydrogen gas and harmful products, thereby spoiling the food.

Solution 2

Curd and sour food substances contain acids; these acidic substances have a possibility of reacting with the metal. If this reaction takes place then it can cause food poisoning and damage people’s health

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Chapter 2: Acids, Bases and Salts - Intext Questions [Page 22]


NCERT Science Class 10
Chapter 2 Acids, Bases and Salts
Intext Questions | Q 1 | Page 22

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Dilute NaOH can be tested with
(a) red litmus paper
(b) blue litmus paper
(c) lime water
(d) Na2CO3

  Column A   Column B
i eosin 1 losing hydrogen
ii oxidation 2 synthetic indicator
    3 losing oxygen
    4 natural indicator


When phenolphthalein is added to NaOH, the colour of the solution will become _________.

  1. colourless
  2. red
  3. pink
  4. yellow

From which plant is litmus paper or litmus solution obtained?

  1. Moss
  2. Rose
  3. Hibiscus
  4. Lichen

While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

The litmus paper or the litmus solution is obtained from ________ plant

(A) Moss

(B) Lichen

(C) Rose

(D) Hibiscus

Fill in the blank in the following sentences:

Substances do not show their acidic properties without.......................... .

 Hydrochloric acid reacts with a metal X to form a gas Y which burns with a 'pop' sound. Sodium hydroxide solution also reacts with the same metal X (on heating) to form the same gas Y.

Write the chemical equation of the reaction of metal X with (i) hydrochloric acid, and (ii) sodium hydroxide solution.

What is the chemical formula of baking soda?

Complete and balance the following chemical equations:

`Ca(OH)_2 + Cl_2 ->`

Explain why, sodium hydrogencarbonate is used as an antacid.


Write the chemical formula of washing soda. How can it be obtained from baking soda? List two industries in which washing soda is used for other purposes than washing clothes. 

Phenolphthalein is a synthetic type of indicator.

Choose the correct alternative and rewrite the following sentence.

Phenolphthalein is ___________ type of indicator. 

When _______________ is passed through fresh lime water, it turns milky.

Answer the following question:
What is the universal indicator? Does Mg (OH)2 react with sodium hydroxide? If not, why?

With the help of suitable examples explain the term neutralization and the formation of –

  1. acidic,
  2. basic and
  3. neutral salts

Magnesium hydroxides are used for treating _______

Write any four physical properties of acids.

Acids turn blue litmus paper to ______.

What is a neutralization reaction? Give an example.

What happens when a solution of an acid is mixed with a solution of a base in a test tube?

  1. The temperature of the solution increases
  2.  The temperature of the solution decreases
  3.  The temperature of the solution remains the same
  4. Salt formation takes place

Acids present in fruits and vegetables are called ______ acids.

Vinegar is ______ in taste.

A salt may be ______.

Solutions of acids conduct ______.

______ change the colour of the indicators.

Which acid is present in milk?

Can we taste acids and bases to identify them?

Take a clean test tube with a holder and pour some dilute hydrochloric acid. Add a few pieces of magnesium ribbon pieces slowly. What do you observe? Now show a burning match stick near the mouth of the test tube. Do you hear any sound? The gas burns with a pop sound. From this, it is observed that hydrogen gas has been formed due to the reaction between acid and metal.

What is the correct procedure for mixing acid and water? Why?

“All acids contain one or more hydrogen atoms, but not all substances containing hydrogen are acids.” Support this statement with examples.

______ & ______ metals do not react with HCl or HNO3.

The formula of bleaching powder is  ______.

The taste of acid is ______.

Write notes on the properties of acids.

A substance 'X' is used as a building material and is insoluble in water. When it reacts with dil. HCl, it produces a gas which turns lime water milky.

  1. Write the chemical name and formula of 'X'.
  2. Write chemical equations for the chemical reactions involved in the above statements.

The metal that will not produce hydrogen gas when reacted with dilute acids.


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