Why are Potassium and Cesium rather lithium can be used in photoelectric cell?
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Give reasons (a) Platinum, gold and silver are used to make jewellery. (b) Sodium, potassium and lithium are stored under oil.
(a) Platinum, gold, and silver are used to make jewellery because they are very lustrous. Also, they are very less reactive and do not corrode easily. (b) Sodium, potassium, and lithium...
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(a) Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements?
(a) Yes. The atoms of all the three elements lithium, sodium, and potassium have one electron in their outermost shells. (b) Both helium (He) and neon (Ne) have filled outermost shells....
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Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
The resistivity of an alloy is higher than the pure metal and it does not corrode easily. Moreover, even at high temperatures, the alloys do not melt readily. Hence, the...
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Why are potassium and cesium, rather than lithium used in photoelectric cells?
Smaller in size and therefore, requires high energy to lose an electron. Pottasium and caesium have much lower ionization enthalpy than that of lithium as a result, these metals exposure to light, easily emit electrons but lithium doesn`t...
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Bone matrix is rich in (a) fluoride and calcium (b) calcium and phosphorus (c) calcium and potassium (d) phosphorus and potassium
(b) calcium and phosphorus
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Potassium chlorate (KCIO3) on heating forms potassium chloride and oxygen. Write a balanced equation for this reaction.
2KCIO3 (s) ------>2KCl(s ) + 3O2(g)
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Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal
Coils of electric toasters and electric irons are made of an alloy rather than a pure metal because (i) the resistivity of an alloy is much higher than that of pure...
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Give reasons: Sodium, potassium and lithium are stored under oil.
Sodium, potassium and lithium are stored under oil to prevent their reaction with oxygen, moisture and carbon dioxide of air so as to protect them as they are highly reactive...
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If the wavelength of light in an experiment on photoelectric effect is doubled, (a) the photoelectric emission will not take place
(b) the photoelectric emission may or may not take place (d) the stopping potential will decrease.
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Two lithium nuclei in a lithium vapour at room temperature do not combine to form a carbon nucleus because
(d) Coulomb repulsion does not allow the nuclei to come very close.
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