Multiple Choice QuestionsA man goes door to door posing as a goldsmith. He promises to bring back the glitter on dull gold ornaments. An unsuspecting woman gives a set of gold bangles to him which he dips in a particular solution. The bangles sparkle but their weight has considerably reduced. The solution used by the impostor probably is
conc. HCl
a mixture of conc. HCl and conc. HNO3
conc. HNO3
dil. HCl
A teacher plans to teach 'Components of Food' in Class-VI. Which of the following can be used as an essential question?
Why does your mother serve you a meal with a variety of food items?
Does your mother prepare a definite set of food items for lunch every day?
Do you eat all the items served in your lunch every day?
List the food items your mother serves you in lunch
When an iron nail is dipped in copper sulphate solution, the colour of copper sulphate solution fades and a brownish layer is deposited over the iron nail. This is an example of
decomposition reaction
double displacement reaction
displacement and redox reactions
combination reaction
Bleeding is stopped by the application of alum to a wound because
alum coagulates the blood and forms a clot
alum reduces the temperature near the wound
alum is an antiseptic
the wound is plugged by the alum chunk
Non-metallic oxides
are basic in nature
are amphoteric in nature
turn red litmus paper blue
are acidic in nature
A doctor prescribes a medicine to treat hyperacidity. The main ingredient of the medicine is
MgCl2
CaCO3
Na2CO3
Al(OH)3
The inner surfaces of food cans are coated with tin and not with zinc because
zinc is more reactive than tin
zinc has a higher melting point than tin
zinc is less reactive than tin
zinc is costlier than tin
While diluting sulphuric acid, it is recommended that the acid should be added to water because
acid may break the glass container
dilution of acid is highly exothermic
dilution of acid is highly endothermic
acid has strong affinity for water
Given below are a few chemical processes
A. Rusting of iron
B. Burning of a candle
C. Respiration
D. Photosynthesis'
Which two of these represent slow combustion?
D and A
A and C
B and C
B and D
B.
A and C
The reaction of an element or compound with an excess of oxygen is called combustion and the combustion process which takes a long time is called slow combustion.
(A)Rusting of iron involves the conversion of iron (Fe) into Fe2O3.xH2O (rust) and takes a longer time, so it is a slow combustion process.
(B)Burning of a candle does not take a longer time, so it is not a slow combustion process.
(C) Respiration involves the breaking down of glucose into CO2 and H2O by O2 and takes a longer time, so it is a slow combustion process.
(D) Photosynthesis, on the other hand, involves the reaction of carbon dioxide and water to give carbohydrate, so it is not a combustion process.
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