206. Which gas is formed on lightning ?

1. 1. N₂O

   
   
   

   2. NO

   
   
   

   3. NO₂

   
   
   

   4. N₂O₅

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

---

207. The chemical used for cooling in refrigeration is

1. 1. CO₂

   
   
   

   2. NH₂OH

   
   
   

   3. NH₂CI

   
   
   

   4. La.NH₃

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

---

---

208. The compound used as refrigerant is

1. 1. CF₄

   
   
   

   2. CCI₄

   
   
   

   3. CCI₂F₂

   
   
   

   4. COCI₂

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

---

209. Which of the following is the second most abundant element in the earth's crust

1. 1. Silicon

   
   
   

   2. Carbon

   
   
   

   3. Nitrogen

   
   
   

   4. Oxygen

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

---

---

210. In laboratory, sulphur dioxide is prepared by

1. 1. FeS₂ + O₂

   
   
   

   2. S + O₂

   
   
   

   3. FeS + H₂SO₄

   
   
   

   4. Cu + H₂SO₄

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

---