CHOOSE

Paheli had bottle of pickle. She tried to open the metal cap to taste it but could not do so. She then took a bowl of hot water and immersed the upper end of the bottle in it for five minutes. she was able to open why?

A substance present in plants which itself does not undergo any change but helps in changing water and carbon dioxide into food. A) Flower B) Bud C) Leaf D) Chlorophyll

Iron blade of spade is made slightly smaller than the wooden handle because: A) Iron ring contracts on heating. B) Iron ring expands on heating. C) Iron ring remains the same on heating. D) Wooden handle expands on heating.

A piece of iron is heated till it becomes red-hot. it then becomes soft and is beaten to a desired shape. What kind of changes are observed in this process-reversible or irreversible?

Which among the following is incorrect statement? A) Rusting of iron is irreversible change. B) Ripening of fruits is a chemical change. C) Breaking of glass is a reversible change. D) All the above E) None of these

Which one of the steps while burning a candle is not reversible? (a) Melting of solid wax (b) liquid wax changes into vapours (c) Wax vapour bums into flame (d) All of these

A potter working on his wheel shaped a lump of clay into a pot. He then baked the pot in an oven. Do these two acts lead to the same kind of changes or different? Give your opinion and justify your answer.

Heat can change: (a) state of an object (b) size of an object (c) solubility of a substance (d) all of these

choose the option

The brown coloured deposition on an iron box when kept in humid air for some days is called: A) Dust B) Rust C) Argon D) All the above

Which kind of change it will be, if a sac of cement gets wet completely and left in open? A) Irreversible change B) Reversible change C) Biological change D) Desirable change

Rusting of iron is an example of: