HSC Science (Computer Science) 11th Standard - Maharashtra State Board Question Bank Solutions

Write relation between decay constant of a radioelement and its half-life.

Derive the relationship between half-life and decay constant of a radioelement.

Decay constant of ¹⁹⁷Hg is 0.017 h^-1. What is its half-life?

The half-life of ¹⁸F is 110 minutes. What fraction of ¹⁸F sample decays in 20 minutes?

The half-life of ³⁵S is 87.8 d. What percentage of ³⁵S sample remains after 180 d?

The half-life of ⁶⁷Ga is 78 h. How long will it take to decay 12% of the sample of Ga?

0.5 g sample of ²⁰¹Tl decays to 0.0788 g in 8 days. What is its half-life?

65% of ¹¹¹In sample decays in 4.2 d. What is its half-life?

A 3/4 of the original amount of radioisotope decays in 60 minutes. What is its half-life?

A sample of ³²P initially shows activity of one Curie. After 303 days, the activity falls to 1.5 × 10⁴ dps. What is the half-life of ³²P?

The half-life of radon is 3.82 d. By what time would 99.9% of radon will be decayed?

A sample of old wood shows 7.0 dps/g. If the fresh sample of tree shows 16.0 dps/g, how old is the given sample of wood? (Half-life of ¹⁴C is 5730 y)

Explain the following.

The ionic radii of F^Θ and Na^⊕ are 133 and 98 pm, respectively.

Explain the following.

The atomic radii of Cl, I, and Br are 99, 133, and 114 pm, respectively.

Explain the following.

Cu forms coloured salts while Zn forms colourless salts.

Explain the following.

₁₃Al is a metal, ₁₄Si is a metalloid and ₁₅P is a nonmetal.

Answer the following.

Ionization enthalpy of Li is 520 kJ mol^-1 while that of F is 1681 kJ mol^-1. Explain.

Answer the following.

Explain the screening effect with a suitable example.

Answer the following.

Why the second ionization enthalpy is greater than the first ionization enthalpy?

Answer the following.

Why the elements belonging to the same group do have similar chemical properties?