Class 10 Science - Questions 101 to 150 | CHAPTER-1

Questions 101 - 150

101. Which of the following is a combination reaction?

(A) CaO + H₂O → Ca(OH)₂
(B) CaCO₃ → CaO + CO₂
(C) Zn + CuSO₄ → ZnSO₄ + Cu
(D) AgNO₃ + NaCl → AgCl + NaNO₃

Answer: (A)

102. Which gas is evolved when zinc reacts with dilute sulphuric acid?

(A) Oxygen
(B) Hydrogen
(C) Nitrogen
(D) Carbon dioxide

Answer: (B)

103. The chemical formula of rust is generally represented as:

(A) FeO
(B) Fe₃O₄
(C) Fe₂O₃·xH₂O
(D) FeS

Answer: (C)

104. Which of the following is a decomposition reaction?

(A) 2H₂ + O₂ → 2H₂O
(B) CaCO₃ → CaO + CO₂
(C) Zn + CuSO₄ → ZnSO₄ + Cu
(D) HCl + NaOH → NaCl + H₂O

Answer: (B)

105. A reaction in which one element displaces another element from its compound is called:

(A) Combination
(B) Decomposition
(C) Displacement
(D) Neutralisation

Answer: (C)

106. Which of the following metals commonly forms a green coating when exposed to moist air for a long time?

(A) Copper
(B) Iron
(C) Aluminium
(D) Silver

Answer: (A)

107. The black coating formed on copper when heated in air is:

(A) Cu₂O
(B) CuO
(C) CuCO₃
(D) CuSO₄

Answer: (B)

108. Which of the following reactions is a double displacement reaction?

(A) Zn + H₂SO₄ → ZnSO₄ + H₂
(B) CaO + H₂O → Ca(OH)₂
(C) Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
(D) 2KClO₃ → 2KCl + 3O₂

Answer: (C)

109. The reaction between an acid and a base is generally called:

(A) Oxidation
(B) Neutralisation
(C) Displacement
(D) Decomposition

Answer: (B)

110. Which gas is produced during the thermal decomposition of calcium carbonate?

(A) H₂
(B) O₂
(C) CO₂
(D) N₂

Answer: (C)

111. What is the colour of copper sulphate solution?

(A) Green
(B) Blue
(C) Yellow
(D) Brown

Answer: (B)

112. When an iron nail is dipped in copper sulphate solution, the solution gradually becomes:

(A) Colourless
(B) Greenish
(C) Yellow
(D) Black

Answer: (B)

113. Which metal is more reactive than copper?

(A) Silver
(B) Gold
(C) Zinc
(D) Platinum

Answer: (C)

114. Oxidation can be defined as:

(A) Addition of oxygen
(B) Removal of oxygen
(C) Addition of hydrogen
(D) Removal of carbon

Answer: (A)

115. Reduction involves:

(A) Addition of oxygen
(B) Removal of oxygen
(C) Addition of carbon dioxide
(D) Formation of acid

Answer: (B)

116. In the reaction CuO + H₂ → Cu + H₂O, CuO is:

(A) Oxidised
(B) Reduced
(C) Neutralised
(D) Decomposed

Answer: (B)

117. In the reaction CuO + H₂ → Cu + H₂O, hydrogen is:

(A) Oxidised
(B) Reduced
(C) Unchanged
(D) Decomposed

Answer: (A)

118. A reaction involving both oxidation and reduction is called:

(A) Combination reaction
(B) Redox reaction
(C) Displacement reaction
(D) Precipitation reaction

Answer: (B)

119. Which of the following is an exothermic reaction?

(A) Photosynthesis
(B) Respiration
(C) Thermal decomposition
(D) Electrolysis of water

Answer: (B)

120. Which process absorbs energy from the surroundings?

(A) Respiration
(B) Burning of fuel
(C) Photosynthesis
(D) Neutralisation

Answer: (C)

121. The reaction 2AgCl → 2Ag + Cl₂ in sunlight is an example of:

(A) Combination
(B) Photochemical decomposition
(C) Displacement
(D) Neutralisation

Answer: (B)

122. Silver chloride is:

(A) Black
(B) White
(C) Green
(D) Blue

Answer: (B)

123. On exposure to sunlight, silver chloride turns:

(A) Red
(B) Grey
(C) Blue
(D) Green

Answer: (B)

124. Which chemical reaction is used in photography?

(A) Decomposition of silver halides
(B) Combination of calcium oxide
(C) Neutralisation
(D) Displacement of copper

Answer: (A)

125. The white precipitate formed in the reaction AgNO₃ + NaCl → AgCl + NaNO₃ is:

(A) AgNO₃
(B) NaCl
(C) AgCl
(D) NaNO₃

Answer: (C)

126. A reaction that produces an insoluble solid is called:

(A) Precipitation reaction
(B) Combination reaction
(C) Redox reaction
(D) Combustion reaction

Answer: (A)

127. Which gas supports combustion?

(A) Nitrogen
(B) Oxygen
(C) Hydrogen
(D) Carbon dioxide

Answer: (B)

128. Which gas is necessary for rusting of iron?

(A) Oxygen
(B) Nitrogen
(C) Hydrogen
(D) Helium

Answer: (A)

129. Rusting of iron can be prevented by:

(A) Painting
(B) Oiling
(C) Galvanisation
(D) All of these

Answer: (D)

130. Galvanisation involves coating iron with:

(A) Copper
(B) Zinc
(C) Silver
(D) Aluminium

Answer: (B)

131. Which metal is used for galvanising iron?

(A) Zinc
(B) Copper
(C) Silver
(D) Gold

Answer: (A)

132. Rancidity is caused mainly due to:

(A) Reduction
(B) Oxidation
(C) Neutralisation
(D) Decomposition by heat

Answer: (B)

133. Rancidity can be prevented by:

(A) Keeping food exposed to air
(B) Adding antioxidants
(C) Increasing temperature
(D) Adding water

Answer: (B)

134. Which gas is commonly filled in packets of chips to prevent rancidity?

(A) Oxygen
(B) Nitrogen
(C) Hydrogen
(D) Carbon dioxide

Answer: (B)

135. The process of gaining oxygen is called:

(A) Reduction
(B) Oxidation
(C) Neutralisation
(D) Precipitation

Answer: (B)

136. The process of losing oxygen is called:

(A) Oxidation
(B) Reduction
(C) Combustion
(D) Sublimation

Answer: (B)

137. Which of the following acts as a reducing agent in the reaction CuO + H₂ → Cu + H₂O?

(A) H₂
(B) O₂
(C) CuO
(D) H₂O

Answer: (A)

138. Which substance acts as an oxidising agent in CuO + H₂ → Cu + H₂O?

(A) H₂
(B) CuO
(C) Cu
(D) H₂O

Answer: (B)

139. The reaction 2Mg + O₂ → 2MgO is:

(A) Combination and oxidation
(B) Decomposition
(C) Double displacement
(D) Neutralisation

Answer: (A)

140. Magnesium ribbon is cleaned before burning because it has a layer of:

(A) Magnesium sulphate
(B) Magnesium oxide
(C) Magnesium chloride
(D) Magnesium carbonate

Answer: (B)

141. Magnesium burns in air with a:

(A) Dull red flame
(B) Dazzling white flame
(C) Green flame
(D) Yellow flame

Answer: (B)

142. The product formed when magnesium burns in oxygen is:

(A) MgCO₃
(B) MgO
(C) MgCl₂
(D) MgSO₄

Answer: (B)

143. Which reaction represents combustion?

(A) CH₄ + 2O₂ → CO₂ + 2H₂O
(B) CaCO₃ → CaO + CO₂
(C) Zn + CuSO₄ → ZnSO₄ + Cu
(D) AgNO₃ + NaCl → AgCl + NaNO₃

Answer: (A)

144. Which of the following is NOT a chemical change?

(A) Burning of coal
(B) Rusting of iron
(C) Melting of ice
(D) Digestion of food

Answer: (C)

145. Which of the following is a chemical change?

(A) Cutting paper
(B) Melting wax
(C) Rusting of iron
(D) Boiling water

Answer: (C)

146. A balanced chemical equation obeys the law of:

(A) Conservation of mass
(B) Conservation of volume
(C) Conservation of pressure
(D) Conservation of temperature

Answer: (A)

147. In a balanced chemical equation, the number of atoms of each element is:

(A) Greater on reactant side
(B) Greater on product side
(C) Equal on both sides
(D) Always zero

Answer: (C)

148. Which symbol represents a gaseous state in a chemical equation?

(A) (s)
(B) (l)
(C) (g)
(D) (aq)

Answer: (C)

149. Which symbol represents an aqueous solution?

(A) (s)
(B) (l)
(C) (g)
(D) (aq)

Answer: (D)

150. Which of the following represents a correctly balanced equation?

(A) H₂ + O₂ → H₂O
(B) 2H₂ + O₂ → 2H₂O
(C) H₂ + 2O₂ → H₂O
(D) 2H₂ + 2O₂ → H₂O

Answer: (B)

Oil and fat containing food items are flushed with nitrogen. Why?

🥫 Oil and Fat Containing Food Items are Flushed with Nitrogen

तेल और वसा युक्त खाद्य पदार्थों में नाइट्रोजन क्यों भरी जाती है?
Class 10 Science | Chemical Reactions and Equations

1️⃣ Full Original Question

Question:

Oil and fat containing food items are flushed with nitrogen. Why?

Hindi:
तेल और वसा युक्त खाद्य पदार्थों में नाइट्रोजन गैस क्यों भरी जाती है?

Chapter: Chemical Reactions and Equations
Class: 10th CBSE Science

2️⃣ Concept — पहले पूरा Concept समझें

Step 1: Oils and fats can react with oxygen present in air.
तेल और वसा वायु में उपस्थित ऑक्सीजन से अभिक्रिया कर सकते हैं।

Step 2: This oxidation causes rancidity.
इस oxidation के कारण rancidity अर्थात विकृतगंधिता होती है।

Step 3: Rancid food develops unpleasant smell and taste.
भोजन की गंध और स्वाद खराब हो जाता है।

Step 4: Nitrogen reduces the contact of food with oxygen.
नाइट्रोजन भोजन का oxygen से संपर्क कम करती है।

⭐ Therefore nitrogen is filled in packets to prevent or slow down rancidity.

3️⃣ Attractive Animation

Nitrogen Protects Oil & Fat from Oxidation

🥔 FOOD PACKET
Oil + Fat

→

N₂
Nitrogen

🛡️ Less Oxygen → Less Oxidation → Less Rancidity

4️⃣ Full Step-by-Step Solution

Complete Answer:

Oil and fat containing food items are flushed with nitrogen to prevent or slow down rancidity. Rancidity is caused by oxidation of fats and oils by oxygen present in air. Nitrogen reduces the contact of food with oxygen and therefore slows down oxidation. Hence the food remains fresh for a longer period.

Fats/Oils + O₂ → Oxidation → Rancidity

Step 1: Fats and oils are susceptible to oxidation.

Step 2: Oxygen reacts with fats and oils.

Step 3: Oxidation causes rancidity.

Step 4: Nitrogen is filled inside the packet.

Step 5: Oxygen contact becomes very low.

Step 6: Oxidation becomes slower.

Step 7: Rancidity is prevented or delayed.

5️⃣ हिंदी में पूर्ण समाधान

तेल और वसा युक्त खाद्य पदार्थों में नाइट्रोजन इसलिए भरी जाती है ताकि विकृतगंधिता (Rancidity) को रोका या धीमा किया जा सके।

वायु में उपस्थित ऑक्सीजन तेल और वसा का oxidation कर सकती है। इससे भोजन का स्वाद और गंध खराब हो जाती है।

नाइट्रोजन भोजन और ऑक्सीजन के बीच संपर्क को कम करती है। इसलिए oxidation की गति कम हो जाती है और food अधिक समय तक fresh रहता है।

6️⃣ CBSE Board Exam — लिखने योग्य उत्तर

Answer:

Oil and fat containing food items are flushed with nitrogen to prevent rancidity. Rancidity is caused by oxidation of fats and oils by oxygen present in air. Nitrogen reduces the contact of food with oxygen and hence slows down oxidation.

Hindi:

तेल और वसा युक्त खाद्य पदार्थों में नाइट्रोजन इसलिए भरी जाती है क्योंकि यह ऑक्सीजन के संपर्क को कम करती है। इससे तेल और वसा का oxidation धीमा होता है तथा rancidity को रोकने या कम करने में मदद मिलती है।

7️⃣ 50 MCQ — CBSE + Foundation Competitive Practice

8️⃣ 1 Mark Questions — 10 Questions

9️⃣ 2 Marks Questions — 10 Questions

🔟 3 Marks Questions — 10 Questions

1️⃣1️⃣ 4 Marks Questions — 10 Questions

1️⃣2️⃣ 5 Marks Questions — 10 Questions

1️⃣3️⃣ 6 Marks Questions — 10 Questions

🏆 Final CBSE Revision

Most Important Chain:

O₂ → Oxidation of Fats/Oils → Rancidity → Bad Taste & Smell

Protection:

N₂ → Less Oxygen Contact → Less Oxidation → Less Rancidity

One-Line Answer:

Oil and fat containing food items are flushed with nitrogen to prevent or slow down rancidity by reducing their contact with oxygen.

तेल और वसा युक्त खाद्य पदार्थों में नाइट्रोजन ऑक्सीजन के संपर्क को कम करके विकृतगंधिता को रोकने या धीमा करने के लिए भरी जाती है।