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प्रश्न
State what you would observe when the following substance is heated in a glass test tube Copper (II) carbonate Red lead .
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उत्तर
CuCO3 → CuO + CO2 ↑
The blue-green powder turns black and a colourless gas is evolved which extinguishes a burning flame.
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संबंधित प्रश्न
Changes in which new substances are formed are called ______ changes.
How do the following help in bringing about a chemical change?
pressure.
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
Write the missing reactants and products and balance the equations.
................+ HCI `→` NaCI + `"H"_2"O"` + .........................
FILL IN THE BLANK
Positively charged ions are called ........
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Potassium fluoride
Define a photochemical reaction.
Write the chemical reaction where the following changes are observed.
Gas is evolved
State the type of reactions for the following represent and balance the ones that are not balanced.
NaOH + HCl → NaCl + H2O
Give a word equation for the following reaction.
A salt which reacts with ammonium hydroxide to give a reddish brown precipitate.
Complete the table given below.
| Flame test for calcium chloride | Acid used for flame test |
State the following reaction represent oxidation or reduction.
\[\ce{Fe++->Fe+++}\]
State the following reaction represent oxidation or reduction.
\[\ce{Cu++->Cu}\]
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].
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
Write some materials prepared by chemical changes.
Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
Classify the following as physical or chemical properties
Most metal oxides form alkalis on interacting with water.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think formation of rust from iron is a chemical change?
The chemical formula of rust is ______.
