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Question 1 (Concept + Limiting Reagent):

A mixture contains 4 g H₂ and 32 g O₂.
They react according to:
2H2+O2= 2H2O
Find:
(i) Limiting reagent
(ii) Mass of water formed
(iii) Mass of excess reactant left

Question 2 (Gas + Stoichiometry + Trick)

At STP, 11.2 L of a gaseous hydrocarbon reacts completely with excess O₂ to produce 44 g CO₂.
Identify the hydrocarbon.

Question 3 (Equivalent + Redox + Stoichiometry )

A 10 g mixture of Na₂CO₃ and NaHCO₃ is completely neutralised by 200 mL of 1 N HCl.
Find the mass percentage of Na₂CO₃ in the mixture.

#SIGNIFICANTFIGURES

Question :1 Evaluate the result with correct significant figures:
(2.36+0.040) +1.2

Question 2
The mass of a cube is measured as 2.50 g and each edge is measured as 1.20 cm.
Calculate the density of the cube with correct significant figures.

Question :1 Identify the correct set of statements:
Reaction: 2Al+ fe2o3 =Al2O3+ 2Fe
A. 54 g Al reacts completely with 160 g Fe₂O₃
B. 27 g Al produces 56 g Fe
C. If Al is excess, Fe₂O₃ is the limiting reagent
D. Mole ratio Al : Fe = 2 : 3
👉 Correct option(s):
1️⃣ A, B and C
2️⃣ A and B only
3️⃣ B and C only
4️⃣ A, C and D


Question 2 (Limiting Reagent )
A mixture of 4 g H₂ and 16 g O₂ reacts to form water.
A. H₂ is the limiting reagent
B. O₂ is the limiting reagent
C. 18 g H₂O is formed
D. Some H₂ remains unreacted
👉 Correct option(s):
1️⃣ A and C
2️⃣ B and D
3️⃣ A and D
4️⃣ B and C

Identify the correct set of statements related to Group 13 elements:
A. Boron shows anomalous behaviour in its group
B. Aluminium forms Al³⁺ ion easily in aqueous solution
C. Gallium has lower melting point than aluminium
D. Inert pair effect increases from B to Tl
👉 Correct option(s):
1️⃣ A, C and D
2️⃣ A and B
3️⃣ B and C
4️⃣ A, B, C and D


Question:2
Identify the correctly matched pairs:
A. Boron trichloride – strong Lewis acid
B. Aluminium chloride – exists as AlCl₃ in vapour phase
C. Diborane – electron deficient compound
D. Boric acid – monobasic acid
👉 Correct option(s):
1️⃣ A and C
2️⃣ A, C and D
3️⃣ B and D
4️⃣ A, B, C and D

Question:3
Identify the correct statements:
A. +3 oxidation state stability decreases from B to Tl
B. +1 oxidation state stability increases from B to Tl
C. Tl³⁺ is a strong oxidising agent
D. Boron forms stable B³⁺ ion
👉 Correct option(s):
1️⃣ A, B and C
2️⃣ A and D
3️⃣ B and C
4️⃣ A, C and D

A. Diborane has two 3-centre-2-electron bonds
B. All B–H bonds in diborane are equivalent
C. Boranes are electron-deficient compounds
D. Terminal B–H bonds are longer than bridge B–H bonds
👉 Correct option(s):
1️⃣ A and C
2️⃣ A, B and C
3️⃣ B and D
4️⃣ A, C and D


Identify the correct set regarding trihalides of Group 13:
A. Lewis acidity of BX₃ decreases from BF₃ to BI₃
B. BF₃ is a weaker Lewis acid than BCl₃
C. AlCl₃ acts as a Lewis acid
D. Boron trihalides undergo hydrolysis except BF₃
👉 Correct option(s):
1️⃣ A and C
2️⃣ B, C and D
3️⃣ A, B and D
4️⃣ B and C only

Identify the correct statements:
A. B₂O₃ is acidic in nature
B. Al₂O₃ is amphoteric
C. Tl₂O₃ is basic in nature
D. Basic character of oxides decreases down the group
👉 Correct option(s):
1️⃣ A and B
2️⃣ A, B and C
3️⃣ B and D
4️⃣ A, C and D

✅ Answer: Option 1 (A, C and D)
Boron anomalous ✔
Al³⁺ strongly hydrated → aqueous me stable nahi ❌
Ga ka m.p. Al se kam ✔
Inert pair effect down the group increase ✔

✅ Answer: Option 2 (A, C and D)
BCl₃ = strong Lewis acid ✔
AlCl₃ vapour phase me dimer (Al₂Cl₆) ❌
Diborane = electron deficient ✔
Boric acid monobasic ✔


✅ Answer: Option 1 (A, B and C)
+3 down the group unstable ✔
+1 stable due to inert pair ✔
Tl³⁺ easily reduce hota ⇒ strong oxidiser ✔
Boron B³⁺ ion nahi banata ❌

✅ Answer: Option 1 (A and C)
Diborane me 2 banana bonds ✔
Terminal & bridge bonds same nahi ❌
Boranes electron-deficient ✔
Bridge bonds longer hote hain ❌

✅ Answer: Option 2 (B, C and D)
Lewis acidity: BF₃ < BCl₃ < BBr₃ < BI₃ ✔
AlCl₃ = Lewis acid ✔
BF₃ hydrolysis nahi karta ❌ (others karte)
A statement ulta likha ❌

✅ Answer: Option 2 (A, B and C)
B₂O₃ acidic ✔
Al₂O₃ amphoteric ✔
Tl₂O₃ basic ✔
Basic character increase hota hai down the group ❌