Chemistry
Assertion (A): For electrical heating devices like electric iron and heater, alloys are used.
Reason (R): Alloys have a greater resistance and low melting point.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true but R is not the correct explanation of A.
Explanation — Alloys are used for heating devices like electric iron and heater because of its high resistance to electricity. Hence, assertion (A) is true. Generally alloys have great resistance to electricity. Thus, they can produce more heat and alloys also have lower melting point than its individual component. Hence, reason (R) is true.
However, in case of electrical iron and heater, alloys have high melting point to withstand the heat, Hence, reason (R) is not correct explanation of assertion (A).
Related Questions
Assertion (A): Reactive metals like calcium, magnesium cannot be obtained by reduction.
Reason (R): Reactive metals have a great affinity towards oxygen
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Aluminium is obtained from its oxide by electrolysis (Hall-Heroult process).
Reason (R): Aluminium is generally not found in the form of aluminium oxide.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Bronze is used in making medals, statues, etc.
Reason (R): Bronze is hard and easily cast.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Fill in the blanks :
(a) During the concentration of bauxite ore, aluminium goes in …………… (soluble/insoluble) part because of its …………… (acidic/basic/amphoteric) nature.
(b) In Hoope's process, pure aluminium is collected at the …………… (top/bottom) of the electrolytic cell.
(c) Usually …………… (sulphide/carbonate) ores are subjected to …………… (calcination/roasting) which is done in the absence of air
(d) Zinc blende is converted to oxide by …………… (roasting/calcination) process.
(e) Froth floatation process is generally used to concentrate …………… ores (sulphides/carbonate)