Class 11th
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New answer posted
6 months agoContributor-Level 10
1.38 (d) 123.00 has five significant figures. Assertion is wrong statement while reason is a correct statement.
New answer posted
6 months agoContributor-Level 10
All the compounds are crystalline solids and their solubility in water is guided by both lattice enthalpy and hydration enthalpy. In case of sodium and potassium compounds, the magnitude of lattice enthalpy is quite small as compared of sodium and potassium that are mentioned, readily dissolve in water. However, in case of corresponding magnesium and calcium compounds, the cations have smaller sizes and more magnitude of positive charge. This means that their lattice enthalpies are more as compared to the compounds of sodium and potassium. Therefore, the hydroxides and carbonates of these metals are only sparingly soluble in water.
New answer posted
6 months agoContributor-Level 10
This is due to the reason that potassium bicarbonate (KHCO3) formed as an intermediate (when CO2 gas is passed through ammoniated solution of potassium chloride) is highly soluble in water and cannot be separated by filtration.
New answer posted
6 months agoContributor-Level 10
(a) Alkali metals have low ionization enthalpies.
They have a strong tendency to lose 1 electron to form unipositive ions. Thus they show an oxidation state of +1 and are strongly electropositive.
(b) Valence electrons of alkali metals like Na and K easily absorb energy from the
flame and are excited to higher energy levels. When these electrons return to the ground state, the energy is emitted in the form of light.
Magnesium atom has small size so electrons are strongly bound to the nucleus. [ Thus they need large amount of energy for excitation of electrons to higher
energy levels which is not possible in Bunsen flame.
(c)Due to the sma
New answer posted
6 months agoContributor-Level 10
(a) Due to its the lowest ionization energy, Cs is considered as the most electropositive element.
(b) Lithium cannot be used in making photoelectric cells because out of all the alkali metals it has the highest ionization energy and thus cannot emit electrons when exposed to light.
(c) Due to small size, lithium does not form alums
New answer posted
6 months agoContributor-Level 10
Beryllium carbonate is unstable and decomposes to give beryllium oxide and carbon dioxide.
New answer posted
6 months agoContributor-Level 10
The loosely held s-electron in the outermost valence shell of these elements makes them the most electropositive metals which readily give ions, M+ or M2+.
New answer posted
6 months agoContributor-Level 10
Li+ has maximum degree of hydration due to its small size and for this reason lithium salts are mostly hydrated.
New answer posted
6 months agoContributor-Level 10
Hydration energy decreases down the group from Be to Ba and lattice energy remains almost constant.
New answer posted
6 months agoContributor-Level 10
Lithium, sodium, potassium, rubidium, caesium and Francium are group I elements and collectively known as the alkali metals.
They are called as the alkali metals because they form hydroxides on reaction with water which are strongly alkaline in nature.
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