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प्रश्न
______ gas causes tears in our eyes while cutting onions.
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उत्तर
Propanethial s-oxide gas causes tears in our eyes while cutting onions.
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संबंधित प्रश्न
What are (i) positive catalysts and (ii) negative catalysts? Support your answer with one example for each of them.
Name three biochemical catalysts found in the human body.
Give reason.
Acidic soil is treated with quick lime.
FILL IN THE BLANK
Positively charged ions are called ........
Name the type of chemical reaction shown by the following equation:
NaOH + HCl → NaCl + H2O
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
Rusting of iron is a ______ chemical change.
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
The white particles of baking soda disappear when put in lemon juice. This means that it is a ______ change.
What do you understand by precipitation reaction? Explain with examples.
What do you observe when CO2 is passed through lime water first and then a little in excess.
Give reason for the following:
Even though rusting is an exothermic reaction, the heat evolved when an iron nail rusts is unnoticeable.
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Addition of water to quicklime.
The chemical change is ______.
Vanaspati is obtained from vegetable oils by the addition of ______ to the oils.
Heat may evolve or be absorbed during a ______ change.
When magnesium is burnt in the air, a new substance is formed which is ______.
______ occurs in the absence of air and in the presence of micro-organisms such as yeast.
We are advised to not to play with fireworks. Give reason.
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
What are the chemical reactions that occur in everyday life?
