CHEMISTRY THE P-BLOCK ELEMENTS-11th
QUIZ-9
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Chemistry is important because everything you do is chemistry! Even your body is made of chemicals. Chemical reactions occur when you breathe, eat, or just sit there reading. All matter is made of chemicals, so the importance of chemistry is that it's the study of everything..
Chemistry is important because everything you do is chemistry! Even your body is made of chemicals. Chemical reactions occur when you breathe, eat, or just sit there reading. All matter is made of chemicals, so the importance of chemistry is that it's the study of everything..
Q1.Which of the following species have undistorted octahedral structures?
1.SF6
2.PF6-
3.SiF62-
4.SeF6
Select the correct answer using the code below
1.SF6
2.PF6-
3.SiF62-
4.SeF6
Select the correct answer using the code below
Solution
1, 2 and 4
In SF6,sulphur has 12 electron around the central atom, this means that there are 6 pairs of
electrons arranged in octahedral shape with bond angle 90° in F-S-F.
In SeF6, the central Se atom is bonded with 6 fluorine atom with 6 pairs of electron arranged in octahedral shape.
Phosphorus belongs to group 5 so it has 5 electron in valence shell. In PF6−, phosphorus is surrounded by 6 fluorine atoms which contribute 6 electron to valence shell, hence, the
total become 11 electrons along with one negative charge on phosphorous atom. So, with total 12 electron, according to VSEPR PF6− shows undistorted octahedral structures
1, 2 and 4
In SF6,sulphur has 12 electron around the central atom, this means that there are 6 pairs of
electrons arranged in octahedral shape with bond angle 90° in F-S-F.
In SeF6, the central Se atom is bonded with 6 fluorine atom with 6 pairs of electron arranged in octahedral shape.
Phosphorus belongs to group 5 so it has 5 electron in valence shell. In PF6−, phosphorus is surrounded by 6 fluorine atoms which contribute 6 electron to valence shell, hence, the
total become 11 electrons along with one negative charge on phosphorous atom. So, with total 12 electron, according to VSEPR PF6− shows undistorted octahedral structures
Q2.Which of the following compounds has the greatest ionic character?
Solution
SiCl4
SiCl4 has highest ionic character due to difference in electronegativity.
SiCl4
SiCl4 has highest ionic character due to difference in electronegativity.
Q3.Water glass is
Solution
Na2SiO3, CaSiO3
Na2SiO3, CaSiO3
Q4.With excess of Cl2 ammonia forms
Solution
Nitrogen trichloride
In excess of ammonia, chlorine forms ammonium chloride.
8NH3(g) + 3Cl2(g) → 6NH4Cl(s) + N2(g)
But in excess of chlorine, ammonia forms nitrogen trichloride.
3Cl2 + NH3 → NCl3 + 3HCl
Nitrogen trichloride
In excess of ammonia, chlorine forms ammonium chloride.
8NH3(g) + 3Cl2(g) → 6NH4Cl(s) + N2(g)
But in excess of chlorine, ammonia forms nitrogen trichloride.
3Cl2 + NH3 → NCl3 + 3HCl
Q5.Compound used in safety matches is
Solution
Compound used in safety matches is P4S3
Compound used in safety matches is P4S3
Q6.Which of the following statement regarding ortho boric acid (H3BO3) is false?
Solution
It acts as a tribasic acid.
Boric acid, also called hydrogen borate, , is a weak, monobasic lewis acid of boron
Option D only is the wrong statement because it acts as monobasic acid not tribasic.
Hence option D is correct.
It acts as a tribasic acid.
Boric acid, also called hydrogen borate, , is a weak, monobasic lewis acid of boron
Option D only is the wrong statement because it acts as monobasic acid not tribasic.
Hence option D is correct.
Q7.Borax Na2B4O7∙10H2Ois actually
Solution
Na2[B4O5OH4]∙8H2O
Na2[B4O5OH4]∙8H2O
Q8.Pentavalent phosphorus is more stable compared to that of nitrogen even through they belong to same group; it is due to
Solution
Large size of phosphorus atom
Pentavalence in phosphorus is more stable when compared to that of nitrogen even
though they belong to same group is due to large size of phosphorus atom and greater
ability to accommodate electrons.
Large size of phosphorus atom
Pentavalence in phosphorus is more stable when compared to that of nitrogen even
though they belong to same group is due to large size of phosphorus atom and greater
ability to accommodate electrons.
Q9.NO2 is not obtained when following is heated
Solution
2KNO3 ∆ → 2KNO2 + O2
2KNO3 ∆ → 2KNO2 + O2
Q10. Amphoteric oxides are
Solution
SnO, SnO2
Amphoteric oxide is one that reacts with both acids and bases to form salt and water.
Thus, SnO and SnO2 react with both HCl (an acid) and NaOH (base) to give salt and water.
GeO and GeO2 are not well characterized. It is amphoteric dissolving in acids to form germanium(II) salts and in alkali to form trihydroxy germanates or germinates and the GeO has not reacted both the acid and base so GeO is not an Amphoteric.
SnO, SnO2
Amphoteric oxide is one that reacts with both acids and bases to form salt and water.
Thus, SnO and SnO2 react with both HCl (an acid) and NaOH (base) to give salt and water.
GeO and GeO2 are not well characterized. It is amphoteric dissolving in acids to form germanium(II) salts and in alkali to form trihydroxy germanates or germinates and the GeO has not reacted both the acid and base so GeO is not an Amphoteric.
