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प्रश्न
Fill in the blank
A new substance is formed in a _______ change.
उत्तर
A new substance is formed in a chemical change.
APPEARS IN
संबंधित प्रश्न
When carbon dioxide is passed through lime water, it turns milky due to the formation of ______.
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
The gas we use in the kitchen is called liquefied petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change − A), then it burns (Change − B). The following statements pertain to these changes. Choose the correct one.
How do the following help in bringing about a chemical change?
catalyst .
Give reason .
A person suffering from acidity is advised to take an antacid.
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
FILL IN THE BLANK
In a double decomposition precipitation reaction both the reactants must be ............ soluble.
FILL IN THE BLANK
In a ............ change, new substances are formed.
TRUE \ FALSE
Positively charged electrode is called the anode. True or false ?
What are homogenous reactions ?
Is kerosene an electrolyte or a non-electrolyte ?
State four conditions necessary for a chemical reaction to take place.
State what you would observe when the following substance is heated in a glass test tube red lead.
A solution of a substance ‘X’ is used for white washing write the reaction of the substance ‘X’ named in (a) above with water.
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)
Oxygen is a ______ in respiration.
Give an example of a reaction where the following are involved:
Close contact
Give an example of the following chemical changes.
A reaction where colour change is noticed.
Define:
Electrochemical reaction
Give one example
Name: Two nitrates that do not produce nitrogen dioxide on heating.
State the original colour of the following substance and colour of residue obtained after heating.
Lead nitrate
State the original colour of the following substance and colour of residue obtained after heating.
Zinc carbonate
Distinguish by heating the following in dry test tubs.
Zinc nitrate and copper nitrate.
Give balanced equation for the following conversion affected by heat alone on the substance:
Copper carbonate to copper oxide
Classify each of the following, as a physical or a chemical change. Give reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change the colour of black tea by adding lemon juice to it.
(e) Churning of milk cream to get butter.
State whether the following statements are true or false:
When a candle burns, both physical and chemical changes take place.
______ are substances that speed up the process of a chemical change and it will not undergo any change during the course of the reaction.
Magnesium + oxygen → magnesium oxide.
2Mg + O2 → 2Mg O
