NEET Chemistry Study Of Representative Elements Revision Notes

Question. Which of the following properties of red P and white P are related to their structure?
a. Large difference in m.p.
b. Difference in hardness
c. Ignition behavior
d. None of these
Answer : A, B, C

Question. Electrolysis of KH produces H₂ :
a. at the cathode
b. at the anode
c. either at the cathode or at the anode
d. Cannot be predicted
Answer : A, B

Question. In which of the following cases, does N₂ evolve as agaseous product?
a. KNO₃ reacts with K on heating
b. Na₂O₂ reacts with NH₃
c. NH₃ reacts with bleaching powder
d. None of these
Answer : A, B, C

Question. Which of the following form dimeric halides
a. Al
b. Mg
c. In
d. Ga
Answer : A, C, D

Question. Which of the following processes cannot give Cl₂ gas as aproduct?
a. Electrolysis of aq. NaCl
b. Oxidation of conc. HCl by K₂CrO₄
c. Electrolysis of very dilute aq. NaCl
d. Oxidation of conc. HCl by MnO₂
Answer : A, B, C

Question. The temporary hardness of water is caused by which of the following compound(s):
a. CaCl₂
b. Mg(HCO₃)₂
c. Ca(HCO₃)₂
d. MgSO₄
Answer : B, C

Question. Which of the following statements are correct regardingthe diagonal relationship between Al and Be?
a. BeO and Al₂O₃ are amphoteric in nature
b. Carbides of both produce the same gas on hydrolysis
c. Both can form complexes.
d. Hydrides of both the elements are covalent in nature
Answer : A, B, C

Question. Which of the following statements are correct?
a. NO is a diamagnetic liquid
b. B₂ and C₂ are diamagnetic
c. N₂O₄ is diamagnetic
d. BH₃ loses its planarity on dimerization
Answer : A, C

Question. Phosphine is obtained from the following ore
a. Calcium superphosphite
b. Calcium phosphide
c. Potassium phosphide
d. Calcium hypophosphide
Answer : B, C

Question. Which statement is false
a. Electronegativity of fluorine is maximum
b. Electron affinity of fluorine is maximum
c. Melting point of fluorine is minimum
d. Boiling point of fluorine is maximum
Answer : B, D

Question. White phosphorus (P4) has
a. Six P - P single bonds
b. Four P - P single bonds
c. Four lone pairs of electrons
d. PPP angle of 60°
Answer : A, D

Question. Among the members of V A group (N, P, As, Sb and Bi), which of the following properties shows an increase as we go down from nitrogen to bismuth:
a. Stability of +3 oxidation state
b. Reducing character of hydrides
c. Electronegativity
d. Acidic nature of the pentoxide
Answer : A, B

Question. SO₂ is obtained when
a. Oxygen reacts with dilute sulphuric acid
b. Hydrolysis of dilute H₂SO₄
c. Concentrated H₂SO₄ reacts with Na₂SO₃
d. All of these
Answer : B, C

Question. When NaOHis prepared, the gas released is:
a. Cl₂
b. H₂
c. O₂
d. H₂O
Answer : A, B

Question. Ammonia on reaction with hypochlorite anion, can form:
a. NO
b. NH4Cl
c. N₂H₄
d. HNO₂
Answer : B,C

Assertion and Reason

Note: Read the Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:
a. If both assertion and reason are true and the reason is the correct explanation of the assertion.
b. If both assertion and reason are true but reason is not the correct explanation of the assertion.
c. If assertion is true but reason is false.
d. If the assertion and reason both are false.
e. If assertion is false but reason is true.

Question. Assertion: HF, NH₃ and H₂O form intermolecular hydrogen bonding.
Reason: HF, NH₃ and H₂O molecules are bonded in same manner.
Answer : C

Question. Assertion: SeCl₄, does not have a tetrahedral structure.
Reason: Se in SeCl₄ has two lone pairs.
Answer : C

Question. Assertion: H₂O₂ is stored in wax-lined glass.
Reason: Presence of metal surfaces, traces of alkali (present in glass) etc. increases its decomposition.
Answer : A

Question. Assertion: Reaction of SO₂ and H₂S in the presence of Fe₂O₃ catalyst gives elemental sulphur.
Reason: SO₂ is a reducing agent.
Answer : B

Question. Assertion: Calgon is used for removing Ca²⁺ and Mg²⁺ ions from hard water.
Reason: Calgon forms precipitate with Ca²⁺ and Mg²⁺ ions.
Answer : D

Question. Assertion: A nearly tetrahedral arrangement of the orbitals about the oxygen atom allows each water molecule to form hydrogen bonds with as many as four neighbouring water molecules.
Reason: In ice each water molecule form four hydrogen bond as each molecule is fixed in the space.
Answer : A

Question. Assertion: Hard water does not lather with soap.
Reason: In hard water, the sodium stearate of soap changes to the corresponding calcium magnesium salt which precipitates out.
Answer : A

Question. Assertion: Borax bead test is not suitable for Al(III).
Reason: Al₂O₃ is insoluble in water.
Answer : B

Question. Assertion: Ozone is a powerful oxidizing agent in comparison to O₂.
Reason: Ozone is diamagnetic but O₂ is paramagnetic.
Answer : B

Question. Assertion: Halogens do not occur in free-state.
Reason: Halogens are highly reactive.
Answer : A

Question. Assertion: The fluorine has lower reactivity.
Reason: F – F bond has low bond dissociation energy.
Answer : C

Question. Assertion: SiF₆²⁻ is known but SiCl₆²⁻ is not.
Reason: Size of fluorine is small and its lone pair of electrons interacts with d-orbitals of Si strongly.
Answer : A

Question. Assertion: Potassium and caesium are used in photoelectric cells.
Reason: Potassium and caesium emit electrons on exposure to light.
Answer : A

Question. Assertion: Lithium forms Lithium oxide (LIO₂).
Reason: N₂ molecule have unpaired electrons.
Answer : A

Question. Assertion: Liquid NH₃ is used for refrigeration.
Reason: Liquid NH₃ quickly vaporises.
Answer : A

Comprehension Based

Paragraph –I

s-block elements having ns^–1 (alkali metals) or ns² (alkaline earth metals) include Li, Na, K, Rb, Cs, Fr and Be, Mg, Ca, Sr, Ba, Ra respectively. These metals are soluble in NH₃ and their ammonia solution is strongly conducting, paramagnetic as well as show colour. All of these are reactive metals due to low values of ionization energy. The physical properties of alkali metals almost describe a regular trend form Li to Cs whereas no such trend is noticed in alkaline earth metals. Also the properties such as density m.pt, b.pt for alkaline earth metals are more than alkali metals. Li in alkali metals and Be in alkaline earth metals differ markedly in many of their properties with their respective group elements.

Question. The conductivity of alkali metals in liq. NH₃ at –33ºC:
a. Increases with increase in temperature
b. Decrease with increase in temperature
c. Remains same with increase or decrease in temperature
d. Due to ions furnished by metals
Answer : B

Question. Which set of statements are correct?
(I) ΔH_hyd for Sr²⁺ > ΔH_hyd for Ag⁺
(II) Ca(OH₂)is less soluble in water than Ba(OH₂)
(III) Ba²⁺ is more powerful reducing agent than Ca²⁺ in acidic solution
(IV) Ca²⁺ is more powerful reducing agent in alkaline medium
a. I, II, III, IV
b. I, II
c. I, III, IV
d. II, IV
Answer : C

Question. Select the wrong statement:
a. Hydration energy: Mg²⁺ Mg Na⁺
b. λ released during flame colour: Li > Na > K > Rb > Cs
c. Conducting power in solution: Cs⁺ > Rb⁺ > K⁺ Na⁺ Li⁺
d. Density: Be > Mg > Ca > Sr > Ba > Ra
Answer : D

Paragraph –II

Group 14 of periodic table includes C, Si, Se Te and Po. Carbon forms two oxides CO (neutral) and CO₂ (acidic) whereas other members of group 14 forms amphoteric oxides. Both CO and CO₂ are covalent compounds. Si does not form monoxide.

Question. CO although neutral acts as acid as well as π-electron acceptor in the reactions respectively:

a. I, II
b. II, III
c. III, II
c. I, IV
Answer : A 

Question. Which statement is not correct?
a. The CO₂ molecule possesses sp-hybridization and also shows resonating structure
b. The structure of CO is [:C =C:]
c. Ammoniacal CuCl absorbs CO forms adduct product
d. Asphyxia is law level poisoning produced in a atmosphere of CO₂
Answer : D

Question. Which statement is not correct?
a. CO is isoelectronic with N₂ but less reactive than N₂
b. CO is isoelectronic with N₂ and possesses more bond energy
c. CO is isoelectronic with N₂ and more reactive than N₂
d. CO is isoelectronic with N₂ and required for respiration
Answer : A

Paragraph –III

Group 15 includes pnicogens i.e., N, P, As, Sb and Bi elements with ns2np3 configuration. N₂ is gas. All these elements except Bi show allotropy. Phosphorus exists in three allotropic forms, white phosphorus, red phosphorus and black phosphorus. The later being most stable (thermodynamically) form of P. Each member of this forms hydrides of the molecular formula MH₃ .Nitrogen however forms three hydrides NH₃, N₃H and N₂H₄. The thermal stability, basic nature and solubility in water of hydrides (MH₃) however decreases form N to Bi.

Question. The correct order for acidic nature is:
a. NH⁺₄ < PH⁺₄ < AsH ⁺₄
b. NH⁺₄ > PH⁺₄ > AsH⁺₄
c. AsH⁺₄ > NH⁺₄ > PH⁺₄
d. AsH⁺₄ < NH⁺₄ < PH⁺₄
Answer : A

Question. Which hydride of group 15 is most powerful reducing agent?
a. NH₃
b. PH₃
c. AsH₃
d. SbH₃
Answer : D

Question. The correct order of bond angles is:
a. NH₃ > PN₃ > AsH₃ >SbH₃
b. SbH₃ > AsH₃ >PN₃ > NH₃
c. SbH₃ > PN₃ > AsH₃ >NH₃
d. PN₃ > NH₃ > SbH₃ > BiH₃
Answer : A

Paragraph –IV

There are some deposits of nitrates and phosphates in earth’s crust. Nitrates are more soluble in water. Nitrates are difficult to reduce under the laboratory conditions but microbes do it easily. Ammonia forms larger number of complexes with transition metal ions. Hybridization easily explains the ease of sigma donation capability of NH₃ and PH₃. Phosphine is a flammable gas and is prepared form white phosphorus.

Question. Among the following, the correct statement is:
a. Phosphates have no biological significance in humans
b. between nitrates and phosphates, phosphates are less abundant in earth’s crust
c. Between nitrates and phosphates, nitrates are less abundant in earth’s crust
d. Oxidation of nitrates is possible in soil
Answer : C

Question. Among the following, the correct statement is:
a. Between NH₃ and PH₃,NH₃ is a better electron donor because the lone pair of electrons occupies spherical ‘s’ orbital and is less directional
b. Between NH₃ and PH₃,NH₃ is a better electron donor because the lone pair of electrons occupies sp3- orbital and is more directional
c. Between NH₃ and PH₃,NH₃ is a better electron donor because the lone pair of electrons occupies sp3- orbital and is more directional
d. Between NH₃ and PH₃,NH₃ is a better electron donor because the lone pair of electrons occupies spherical ‘s’ orbital and is less directional
Answer : C

Question. White phosphorus on reaction with NaOH gives PH₃ as one of the products. This is a:
a. dimerization reaction
b. disproportionation reaction
c. condensation reaction
d. precipitation reaction
Answer : B

Match the Column

Question. Match the chemical properties with the compounds:

a. A→1,4; B→1,2,3; C→2,3; D→2,3,
b. A→1,3,4; B→1,2,4; C→2,3; D→2,3,4
c. A→1,2,4; B→1,3; C→2,3; D→2,3,4
d. A→1,2,4; B→1,2,3; C→2,3; D→2,3,4
Answer : D

Question. Match the compounds with their uses / properties:

a. A→1,5; B→1,4; C→4; D→2,5
b. A→3,5; B→1,5; C→4; D→2,3
c. A→3,5; B→1,5; C→4; D→2,5
d. A→3,5; B→3,5; C→4; D→1,5
Answer : C

Question. Match the xenon compounds with their properties.

a. A→1,3; B→1,2; C→3; D→3,4
b. A→1,3; B→2,4; C→3; D→3,4
c. A→1,2; B→1,4; C→3; D→3,4
d. A→1,2; B→1,4; C→1; D→1,4
Answer : C

Integer

Question. Among the following elements, the number of elements that release H₂ on reaction with NaOH is …………… Be, Al, B, Mg, Ca, Zn, Sn
Answer : 5

Question. The Among the following compounds, the number of compounds which do not produce acidic or basic solutions which do not produce acidic or basic solutions when dissolved in water is ……………? NaCl₂, BeCl₂ , Li₂ O,MgO,CaH₂, CaSO₄
Answer : 3

Question. The number of bicarbonates that do not exist in solid form among the following is ……………
LiHCO₃, NaHCO₃, Ca(HCO₃)₂ ,KHCO₃, NH4HCO₃, Ba(HCO₃)₂, Mg(HCO₃)₂
Answer : 4

Question. The ratio of the number of water of crystallization in gypsum and that in plaster of Paris is ……………
Answer : 4

Question. The number of planes of symmetry in [BeH₄]^2– is ……………
Answer : 6