Which of the following statement(s) is/are correct regarding recognising a chemical change involving organic compounds?
A. Ripening of fruit
B. Burning of natural gas
C. Formation of steel
Important Questions on Matter and Its States
Consider the following factors on which a phenomenon (X) depends. By studying all the given factors, choose the option which correctly describe phenomenon (X).
1. Surface area 2. Temperature 3. Humidity 4. Wind speed
The phenomenon (X) is _____.
Consider the following statements:
1. Silver articles become black after sometimes when exposed to air because they react with sulphur in the air to form a coating of silver sulphide.
2. Copper reacts with moist carbon dioxide in the air and lose its shiny brown surface and gains a green coat of copper carbonate.
3. Iron when exposed to moist air for a long time, acquires a coating of a brown flaky substance called rust.
Which of the statements given above is/are correct?
Consider the following statements:
1. Reactions in which heat is released along with the formation of products are called exothermic chemical reactions.
2. Reactions in which energy is absorbed, are known as endothermic reactions.
Which of the statements given above is/are correct?
Consider the following statements:
. Rust is formed by the reaction of iron and oxygen in the presence of water or air moisture.
. In saltwater, iron tends to rust more quickly.
Which of the statements given above is/are correct?
When iron is left exposed to open air, it gets rusted. Which constituent(s) of the atmosphere is /are responsible for rusting iron?
(i) Oxygen gas present in the air.
(ii) Moisture present in the air.
(iii) Carbon dioxide gas is present in the air.
Select the correct answer using the code given below:
Consider the following statements:
1. Albo iron does not rust in a vacuum because air is necessary for rusting.
2. Rust is faster in sea water because of dissolved salts.
Which of the statements given above is/are correct?
