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प्रश्न
State four conditions necessary for chemical reactions to take place.
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उत्तर
Conditions necessary for chemical reactions :
- Close contact
- Solution form
- Heat
- Light
- Catalyst
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संबंधित प्रश्न
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Which one of the following alters the rate of the chemical reaction without itself undergoing any change?
- temperature and Pressure
- concentration of reactants
- presence of catalyst
- none of these
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Compounds, which in their molten state allow an electric current to pass through them are called
- electrolytes
- non-electrolytes
- non-conductors
- none of these
Fill in the blank:
The substances which undergo chemical change are called _______
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.
Define an electrochemical reaction.
Give reason for the following:
Silver nitrate solution is kept in coloured bottles.
State the type of reactions for the following represent and balance the ones that are not balanced.
NaOH + HCl → NaCl + H2O
Name: A brown gas
Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves a black residue and evolves two gases one of which is acidic and coloured and the other neutral and colourless.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc carbonate to zinc oxide
Explain with the help of balanced equations, how precipitation reactions are used for identifying the positive radicals in three different salts, each having a different cation [positive ion].
Limestone contains ______ mainly.
Write some materials prepared by chemical changes.
Rusting of iron is ______.
Match the following:
| Column I | Column II | ||
| 1. | Burning of coal | a. | Rusting |
| 2. | Painting of a surface | b. | Evaporation |
| 3. | Dipping iron in the water | c. | Chemical change |
| 4. | Salt from seawater | d. | Prevention of rusting |
Is the conversion of milk into ice cream a chemical change?
Write the chemical reaction of baking soda with lemon.
______ is a chemical substance is used in whitewashing.
