A buffer solution contains 500 mL of 0.2 M CH₃COONa and 500 ml of 0.1 M CH₃COOH .1 L of water is added to this buffer , pH before and after dilution will be (pka of CH₃COOH = 4.74)

• 3.74

• 5.04

• 5.90

• 7.70

What is binding energy in ${}_5{}^{11}\mathrm{B}$ nucleus , if mass is 0.08181 amu ?

• 1.2 x 10^-4 erg/nucleus

• 8.2 x 10^-4 erg/nucleus

• 10.2 x 10^-4 erg/nucleus

• 1.9 x 10^-4 erg/nucleus

Among third row elements , the IP value :

• irregularly changes from left to right across the third row

• increases from left to right across the third row

• decrease for Na to Ar

• remains constant

Hydrofluoric acid shows hydrogen bonding due to :

• high electron affinity of fluorine

• high bond dissociation energy of fluorine

• high electronegativity of fluorine

• none of the above

The conjugate base of (CH₃)₂NH₂⁺ is :

• (CH₃)₃N

• (CH₃)₂NH

• (CH₃)₂N^-

• (CH₃)₂N⁺

Metals are good conductor of electricity because they contain :

• a network structure

• ionic bonds

• very few valence electrons

• free electrons

Which is the strongest acid ?

• ClCH₂COOH

• CH₃COOH

• Cl₂CHCOOH

• CCl₃COOH

18.

Which of the compound is optically active ?

• 1 - butanol

• Ethanol

• 2 - butanol

• Isopropyl alcohol

Crystalline form of silica is called :

• crystalline silicon

• quartz

• rock

• talc

The elements commonly used for making transistors are :

• Ga and In

• C and Si

• P and As

• Si and Ge