Borax

Q. In the following reaction,

$H_{3}C-C\equiv CH\underset{873K}{\overset{redhotirontube}{\to }}A,$
the number of sigma ($\sigma$) bonds present in the product A is :-

1. 9
2. 21
3. 18
4. 24

Q. Which of the following compounds does not show Lassaigne's test for nitrogen?

1. Urea
2. Azobenzene
3. Hydrazine
4. Phenylhydrazine

Q. When borax is heated strongly it gives:

1. $B_2{O}_3$
2. $N{a}_2{B}_4{O}_7$
3. $NaB{O}_2+B_2{O}_3$
4. None of the above

Q.

What is the color of lead nitrate before heating?

Q.

Define water of crystallization? Give the chemical formula for two compounds as examples? How can it be proved that the water of crystallization makes a difference in the state and color of the compounds?

Q.

How many sigma bonds and pi bonds are there in ${\mathrm{C}}_2$(the carbon molecule)?

Q. 2 Aluminium chloride in acidified aqueoussolution forms a complex A, in whichhybridisation state of Al is B. What are Aand B, respectively?(a) \lbrack Al(H20)613, sp^° d(b) \lbrack Al(H2O)43, sp3(c) \lbrack Al(H2O)4\rbrack3, dsp2(d) \lbrack Al(H20)63, d sp

Q. The reaction of formic acid with concentrated $H_{2}S{O}_4$ gives

1. $C{O}_2+H_{2}O$
2. $CO+H_{2}O$
3. $HCHO$
4. $C{H}_{3}COOH$

Q.

How is O₃ estimated quantitatively?

Q. Which of the following compounds is formed in borax bead test?

1. Tetraborate
2. Triborate
3. Metaborate
4. Orthoborate

Q. $\left(a\right)H_2{O}_2+O_3⟶H_{2}O+2O_2\left(b\right)H_2{O}_2+A{g}_{2}O⟶2Ag+H_{2}O+O_2$
Role of hydrogen peroxide in the above reactions is respectively

1. Oxidizing in (a) and (b)
2. Reducing in (a) and oxidizing in (b)
3. Reducing in (a) and (b)
4. Oxidizing in (a) and reducing in (b)

Q. When $I^{-}$ is oxidized by $Mn{O}_4^{-}$ in faintly alkaline medium, $I^{-}$ is converted into

1. $I{O}_3^{-}$
2. $I_2$
3. $I{O}_4^{-3}$
4. $IO$

Q. What is the coordination number of hexagonal close packing (hcp) lattice?

1. 12
2. 8
3. 6
4. 4

Q. In the structure of borax, the numbers of boron atoms and B-O-B units, respectively, are:

1. 4 and 3
2. 5 and 4
3. 5 and 3
4. 4 and 5

Q. When borax is heated with $\text{CoO}$ on a platinum loop, blue coloured bead formed is largely due to :

1. $\text{Co}{\left({\text{BO}}_2\right)}_2$
2. ${\text{B}}_2{\text{O}}_3$
3. $\text{Co}\left[{\text{B}}_4{\text{O}}_5\right(\text{OH}{)}_4]$
4. ${\text{CoB}}_4{\text{O}}_7$

Q. Which of the following is/are method(s) to prepare borax?

1. Dissolving tincal in boiling water
2. Heating colemanite along with soda ash
3. Treating colemanite with sulphuric acid
4. Neutralising boric acid with soda ash

Q. Colour of the bead in borax bead test is mainly due to the formation of:

1. Metal oxides
2. Boron oxide
3. Metal metaborates
4. Elemental boron

Q. Borax bead test is used to identify the:

1. Anion in metal salt
2. Cation in metal salt
3. Salt
4. Metalloid

Q. The ratio of $s{p}^3$ and $s{p}^2$ hybridized atoms in the anionic part of borax is:
(If answer is $12:4$ then represent as $0124$)

Q.

If $10\mathrm{ml}$ of ${\mathrm{H}}_2{\mathrm{SO}}_4$ is mixed with $10\mathrm{ml}$ $\mathrm{Mg}{\left(\mathrm{OH}\right)}_2$ the same concentration the resultant solution will give the following color of universal indicator

1. Red

2. Yellow

3. Green

4. Blue

Q. The correct statements regarding borax is :

1. White crystalline solid
2. More soluble in cold water
3. Less soluble in hot water
4. None of the above

Q. $N{a}_2{B}_4{O}_7.10H_{2}O\stackrel{\Delta }{\to }N{a}_2{B}_4{O}_7++10H_{2}O\stackrel{{740}^{o}C}{\to }2NaB{O}_2+A$, $A+C{r}_2{O}_3\stackrel{\Delta }{\to }B$
$A$ and $B$ respectively are:

1. $N{a}_{3}B{O}_3,M{n}_3(B{O}_3{)}_2$
2. $N{a}_2(B{O}_2{)}_2,Mn(B{O}_2{)}_2$
3. None is correct
4. $B_2{O}_3,Cr(B{O}_2{)}_3$

Q. Match the following forms of borax with the number of water molecule(s) present as water of crystallisation.

1. 10
2. 5
3. \N

Q. Borax is actually made of two tetrahedra and two triangular units joined together and should be written as : $N{a}_2\left[B_4{O}_5\right(OH{)}_4].8H_{2}O$
Consider the following statement about borax:
a. Each boron atom has four $B-O$ bond
b. Each boron atom has three $B-O$ bonds
c. Two boron atoms have four $B-O$ bonds while other two have three $B-O$ bonds
d. Each boron atom has one $-OH$ groups
Select correct statement(s):

1. a, b
2. b, c
3. c, d
4. a, c

Q.

Is $\mathrm{Mn}{\left(\mathrm{OH}\right)}_2$ soluble or insoluble in water?

Q.

Which is a buffer solution

1. CH₃COOH + CH₃COONa

2. CH₃COOH + CH₃COONH₄

3. CH₃COOH + NH₄Cl

4. NaOH + NaCl

Q. The crystalline form of borax has:

1. Tetranuclear $\left[B_4{O}_5\right(OH{)}_4{]}^{2-}$ unit
2. All boron atoms in the same plane
3. Equal number of $s{p}^2$ and $s{p}^3$ hybridized boron atoms
4. One terminal hydroxide per boron atom

Q. Borax bead test is not given by

1. Aluminium Salt
2. Cobalt salt
3. Copper
4. Nickel salt

Q. The radius of a divalent cation $A^{2+}$ is $94pm$ and that of a divalent anion $B^{2-}$ is $146pm$. The coordination number of $AB$ is:

1. 4
2. 6
3. 8
4. 3

Q. Is aqueous solution of borax basic? Explain