Which of the following is the most basic ?

What is the name of the element with atomic number 105?

• Dubnium

• Holmium

• Kurchatovium

• Nobelium

Consider the ground state of Cr atom (Z= 24). The numbers of electrons with the azimuthal quantum numbers, l = 1 and 2 are respectively

• 12 and 4

• 12 and 5

• 16 and 4

• 16 and 5

Sodium bicarbonate on heating decomposes to form sodium carbonate, CO₂ and water. If 0.2 moles of sodium bicarbonate is completely decomposed, how many moles of sodium carbonate is formed?

• 0.1

• 0.2

• 0.05

• 0.025

5.

Intermolecular hydrogen bonding is strongest in

• HCHO

• CH₃OH

• C₆H₅OH

• CH₃NH₂

If standard enthalpies of formation of CaCl (s) (hypothetical) and that of CaCl₂ (s) are -188 J mol^-1 and -795 kJ mol^-1 respectively, calculate the value of standard heat of reaction for the following  disproportionation reaction

2CaCl (s) → CaCl₂ (s) + Ca (s)

• -607 kJ mol^-1

• +607 kJ mol^-1

• -419 kJ mol^-1

• +419 kJ mol^-1

Aluminium chloride exists as dimer, Al₂Cl₆, in solid state as well as in solution of non-polar solvents such as benzene. When dissolved in water, it gives

• Al³⁺ + 3Cl^-

• [Al(H₂O₆]³⁺ + Cl^-

• [Al(HO)₆]^3- + 3HCl

• Al₂O₃ + 6HCl

The ions N^3-, O^2-, F^-, Na⁺, Mg²⁺ are isoelectronic. Their ionic radii show

• an increase from N^3- to F^- and then decrease from N⁺ to Mg²⁺

• a decrease from N^3- to F^- and then increase from Na⁺ to Mg²⁺

• a significant increase from N^3- to Mg²⁺

• a significant decrease from N^3- to Mg²⁺

Which of the following is not true?

• In a first order reaction, the half-life is independent to the initial concentration of reactant.

• A given piece of charcoal shows increase in its surface area in its powdered form.

• In valence bond of H₂, each electron spends its time around its own nucleus

• In valence bond of H₂, both the electrons spend their time around both the nucleus

250 mL of a Na₂CO₃ solution contains 2.65 g of Na₂CO₃ 10 mL of this solution is added to x mL of water to obtain 0.001 M Na₂CO₃ solution.The value of x is (molecular weight of Na₂CO₃ = 106)

• 1000 mL

• 990 mL

• 9990 mL

• 90 mL