Periodic trends in chemical properties - class-XI

Inert gases have very high ionization enthalpy and zero electron gain enthalpy. So the correct answer is He.

Option E is the correct answer.

Group 18 contains noble gases.

Xe is present in 5th period of periodic table.

Zero group elements are the noble gases (He, Ne, Ar, Kr, Xe, Rn). Their atomic numbers are 2, 10, 18, 36, 54, 86. Atomic number 16 corresponds to Sulfur, which is not a noble gas.

Noble gases are chemically inert because they have a stable, complete valence electron shell (octet configuration), making them highly unlikely to gain, lose, or share electrons.

Argon has an atomic number of 18. Its electron configuration is 1s2, 2s2, 2p6, 3s2, 3p6.

While noble gases are generally inert, Xenon is the most reactive among them due to its lower ionization energy, allowing it to form compounds with highly electronegative elements like fluorine and oxygen. Argon, Helium, and Radon are significantly less reactive under standard conditions.

The naturally occurring noble gases are Helium, Neon, Argon, Krypton, Xenon, and Radon. This makes a total of 6 elements.

Helium is an inert gas. Inert gases are not very reactive as their outermost shell is completely filled. $ {He} $ is not very soluble in water.

As per octet rule, noble gases have 8 electrons in their outermost shell. According to octet rule the element which has 8 electron in its valence shell are stable.

Based on the table, Y forms a hydroxide with water (characteristic of Na or Mg), X hydrolyses (characteristic of Al or Si), and Z forms an acid (characteristic of P or S). Matching these properties, Y=Na (forms NaOH), X=Si (SiCl4 hydrolyses), and Z=P (P4O10 forms phosphoric acid) fits the data.

Hydration decreases with a decrement in charge density of an ion

Lithium is lightest elemental metal nearly half as dense as water, so it floats on the surface and ultimately disappears, giving off hydrogen gas and forming a colourless solution of lithium hydroxide.

Sodium reacts with water more vigorously than lithium its more electropositive and will give electrons easily.
Hence option C is correct.

Sodium ions and potassium ions do not react with water.
The main reason is that have already lost that electron and are therefore much more stable. They don't tend to lose another electron, and they certainly don't try to get that lost electron back, so there's no tendency for them to react.

Answer (A)

Lithium and sodium form complex hydrides such as lithium aluminium hydride and sodium borohydride.