Standard XII

Q.

If $\mathrm{y}={\mathrm{x}}^{{\mathrm{x}}^{\mathrm{x}....\infty }},$, then $\frac{\mathrm{dy}}{\mathrm{dx}}$ is equal to

1. ${\mathrm{yx}}^{\mathrm{y}-1}$

2. $\frac{{\mathrm{y}}^2}{\mathrm{x}(1-\mathrm{ylog}\mathrm{x})}$

3. $\frac{\mathrm{y}}{\mathrm{x}\left(1+\mathrm{ylogx}\right)}$

4. None of these

Q. If the female gamete carries 22+XX chromosomes, while male gamete is normal, predict the probable defects in the baby formed as a result of fusion between these gametes from the options given below.

i. Triple X syndrome
ii. Klinefelter’s syndrome
iii. Turner’s syndrome
iv. Edwards' syndrome
[1 mark]

1. i and ii
2. ii and iii
3. i and iv
4. iii and iv

Q.

Calculate(a)molality (b)molarity and (c)mole fraction of KI if the density of 20% (mass/mass) aqueous KI is1.202 g mL^-1.

Q. Calculate the mass of Urea required in making 2.5 kg of 0.25 molal aqueous solution.

Q.

Henrys law constant for $C{O}_2$ in water is $1.6\times {10}^8$ Pa at 298K.

Calculate quantity of $C{O}_2$ in 500 mL of soda water when packed under 2.5 atm $C{O}_2$ pressure at 298K.

Q.

Define nutrition.

Q.

QUESTION 2.5

A solution of glucose in water is labelled as $10\%w/w$. What should be the molality and mole fraction of each component in the solution? If the density of solution is $1.2gm{L}^{-1}$, then what shall be the molarity of the solution?

Q.

What changes did the order from Berlin cause in school that day?

Q.

A charge q is placed at the center of the line joining two equal charges Q. The system of three charges will be in equilibrium if q is equal to

1. $\frac{-Q}{2}$
2. $\frac{-Q}{4}$
3. $\frac{+Q}{2}$
4. $\frac{+Q}{4}$

Q. Four charges equal to – Q are placed at the four corners of a square and a charge q is at its centre. If the system is in equilibrium the value of q is

1. $-\frac{Q}{4}(1+2\sqrt{2})$
2. $\frac{Q}{4}(1+2\sqrt{2})$
3. $\frac{Q}{2}(1+2\sqrt{2})$
4. $-\frac{Q}{2}(1+2\sqrt{2})$

Q.

Explain the importance of the conservation of resources?

Q.

An object is placed at a distance of 10 cm from a convex mirror of a focal length of 15 cm. Find the position and nature of the image.

Q.

Calculate the mole fraction of benzene in a solution containing 30% by mass of carbon tetrachloride

Q.

How are oxygen and carbon dioxide transported in human beings?

Q.

What did Franz notice that was unusual about the school that day?

Q.

QUESTION 2.4

Concentrated nitric acid used in laboratory work is $68\%$ nitric acid by aqueous solution. What should be the molarity of such a sample of the acid if the density of the solution is 1.504 g mL−1mL^{-1}mL−1 ?

Q.

The maximum height of projectile formula is ______.

Q. $H_{2}S$ , a toxic gas with a rotten egg like smell is used for the qualitative analysis. If the solubility of $H_{2}S$ in the water at STP is $0.195m$, then Henry's law constant (in atm) is nearly :

1. 28.94
2. 285
3. 145.2
4. 2890.4

Q. Calculate the molarity of a solution containing $5g\text{of}NaOH\text{in}450mL$ solution.

Q.

The density of 3M solution of NaCl is 1.25 g/mL. Calculate molality of the solution.

Q.

The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

Q.

State henrys law and its applications.

Q.

Define land degradation. Explain with causes and control measures

Q. Find the value of the angle of emergence from the prism. Refractive index of the glass is $\sqrt{3}$.

1. ${90}^{\circ }$
2. ${60}^{\circ }$
3. ${30}^{\circ }$
4. ${45}^{\circ }$

Q. Four charges are arranged at the corners of a square ABCD, as shown in the figure. The force on the positive charge kept at the centre O is

1. zero
2. along the diagonal AC
3. perpendicular to side AB
4. along the diagonal BD

Q. An infinitely long straight conductor carries a current of $5\text{A}$ as shown. An electron is moving with a speed of ${10}^5\text{m/s}$ parallel to the conductor. The perpendicular distance between the electron and the conductor is $20\text{cm}$ at an instant. Calculate the magnitude of the force experienced by the electron at that instant.

1. $8\times {10}^{-20}\text{N}$
2. $4\times {10}^{-20}\text{N}$
3. $8\pi \times {10}^{-20}\text{N}$
4. $4\pi \times {10}^{-20}\text{N}$

Q.

The maximum electric field strength E due to a uniformly charged ring of radius r, happens at a distance x, where value of x is (x is measured from the centre of the ring)

1. x = R

2. $x=\frac{R}{2}$

3. $x=\frac{R}{\sqrt{2}}$

4. $x=\sqrt{2}R$

Q.

Explain how to calculate the number of atoms of a certain element in a given mass of a compound.

Q. What is meant by the word ‘Company’? Describe its characteristics.

Q.

The number of all possible matrices of order $3\times 3$ with each entry 0 to 1 is
(a)27
(b)18
(c)81
(d)512