मराठी
सी.आई.एस.सी.ई.आयसीएसई ICSE Class 7

State What You Would Observe When the Following Substance is Heated in a Glass Test Tube Red Lead - Chemistry

Advertisements
Advertisements

प्रश्न

State what you would observe when the following substance is heated in a glass test tube red lead.

टीपा लिहा

उत्तर

2Pb3O4 → 6PbO + O2 ↑
The dark red lead as red powder changes to yellow colour. The yellow colour residue on further heating sticks to the tube and give reddish colour to glass. A colourless and odourless gas is evolved.

shaalaa.com
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 5: Language of Chemistry - Additional questions

APPEARS IN

सेलिना Concise Chemistry [English] Class 7 ICSE
पाठ 5 Language of Chemistry
Additional questions | Q 6.1

संबंधित प्रश्‍न

How would you show that setting of curd is a chemical change?


Define catalyst.


What are oxides ? 


MULTIPLE CHOICE QUESTIONS

Tick the most appropriate answer.

Reduction reaction is the exact opposite of

  1. displacement reaction
  2. decomposition reaction
  3. oxidation reaction
  4. none of these

MULTIPLE CHOICE QUESTIONS

Tick the most appropriate answer.

Reduction is a chemical reaction in which there is

  1. removal of hydrogen
  2. removal of oxygen
  3. addition of oxygen
  4. none of these

FILL IN THE BLANK

The new substances formed during a chemical reaction are called the ..................


Name three reducing agents ?


What do you observe when :

an iron nail is kept in tap water for few days


True or false 

New substances are formed in a chemical change.


Write true or false .
A black residue is formed when sugar is heated .


Explain the following reaction with one suitable example of Decomposition reaction


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)

An ______ is drawn in between the reactants and products while writing the equation for a chemical reaction.


Give an example of a reaction where the following are involved:

Close contact


Write the chemical reaction where the following changes are observed.

Colour change is noticed


Multiple choice:

A reaction of a type: AB + CD → AD + CD, involves


Give a chemical test to distinguish between the following gases. 

H2 and CO2


Give a chemical test to distinguish between the following gases. 

H2 and O2


Select the correct answer for the following options:

The pale blue precipitated obtained when copper [II] sulphate reacts with sodium hydroxide.


Give reason for the following:

A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.


A chemical reaction is often accompanied by external indications or characteristics which include – 

  1. Colour change
  2. Effervescence or gas evolved
  3. Evolution or absorption of heat
  4. Formation of a precipitate.

With reference to each of the above indications, state the external indication seen during – Addition of water to quicklime.


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 on strong heating a black residue and evolves two colourless gases one of which is acidic and the other neutral.


Give balanced equation for the following conversion affected by heat alone on the substance:

Zinc nitrate to nitrogen dioxide


Complete the table given below.

Flame test for calcium chloride Acid used for flame test  

State the following reaction represent oxidation or reduction.

\[\ce{Cu++->Cu}\]


Explain the term chemical reaction with special reference to reactants and products.


State whether the following statements are true or false:

When a candle burns, both physical and chemical changes take place.


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

We are advised to not to play with fireworks. Give reason.


Write the characteristics of chemical change.


______ is the chemical name of limestone.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×