20. which of the following substances is not a diatomic gas at room temperature? a. o₂ b. cl₂ c. f₂ d. br₂ 21. carbon(ll) oxide is a poisonous gas due to its ability to a. remove oxygen from blood. b. form stable compound with haemoglobin. c. destroy the red blood cells. d. attack haemoglobin of red blood cells. 22. alkenes are relatively more reactive than alkanes because a. alkenes are more stable than alkanes. b. the double bond in alkenes is susceptible to nucleophilic attack. c. the c - h bond in alkenes are more polar than in alkanes. d. there is a high electron density at the double bond in alkenes. 23. the element that has no electron in the p - orbital is a. helium. b. neon. c. nitrogen. d. argon. 24. which of the following statements about group 7 elements is correct? they a. are monoatomic. b. have low electron affinity. c. are highly electronegative. d. are good reducing agents. 25. consider the reaction represented by the equation: 2h₂o₂(l)→2h₂o(l)+o₂(g) the mass of h₂o₂ that would be required to produce 22.4 dm³ of oxygen at s.t.p is o = 16.0, h = 1.0, vm = 22.4 dm³ a. 16 g. b. 34 g. c. 32 g. d. 68 g. 26. which of the following metals can be extracted by electrolysis? a. gold b. copper c. iron d. sodium 27. polymerization of ethyne gives a. benzene. b. polythene. c. cyclohexane. d. polystyrene.

Question

Accepted Answer

### 20.
# Explanation:
## Step1: Recall diatomic gases
Diatomic gases at room - temperature include $O_2$, $Cl_2$, $F_2$, $Br_2$ etc. But $O_2$ is a diatomic gas at room - temperature.
## Step2: Identify the answer
All options A ($O_2$), B ($Cl_2$), C ($F_2$), D ($Br_2$) are diatomic gases at room - temperature. There seems to be an error in the question as no non - diatomic gas is provided among the options. But if we assume a misprint and go by general knowledge, all of these are diatomic.
# Answer: No correct option

### 21.
# Explanation:
## Step1: Understand carbon(II) oxide toxicity
Carbon monoxide ($CO$) is poisonous because it forms a stable compound with haemoglobin. This stable complex, carboxy - haemoglobin, prevents the normal binding of oxygen to haemoglobin.
## Step2: Select the answer
The correct reason is that it forms a stable compound with haemoglobin.
# Answer: B. form stable compound with haemoglobin

### 22.
# Explanation:
## Step1: Analyze alkene reactivity
Alkenes have a double bond ($C = C$). The double bond has a high electron density due to the presence of a $\pi$ - bond. This high electron density makes alkenes more reactive towards electrophiles.
## Step2: Choose the answer
The high electron density at the double bond in alkenes makes them relatively more reactive than alkanes.
# Answer: D. there is a high electron density at the double bond in alkenes

### 23.
# Explanation:
## Step1: Write electron configurations
Helium has an electron configuration of $1s^2$. Neon has an electron configuration of $1s^22s^22p^6$. Nitrogen has an electron configuration of $1s^22s^22p^3$. Carbon has an electron configuration of $1s^22s^22p^2$. Helium has no electrons in the $p$ - orbital.
## Step2: Determine the answer
The element with no electrons in the $p$ - orbital is helium.
# Answer: A. helium

### 24.
# Explanation:
## Step1: Recall properties of group 7 elements
Group 7 elements (halogens) are diatomic ($X_2$), not monoatomic. They have high electron affinities as they are one electron short of a stable noble - gas configuration. They are highly electronegative. They are good oxidizing agents, not reducing agents.
## Step2: Select the answer
Halogens have high electron affinities.
# Answer: B. have low electron affinity

### 25.
# Explanation:
## Step1: Write the balanced chemical equation and mole ratios
The balanced equation is $2H_2O_2(l)
ightarrow2H_2O(l)+O_2(g)$. At s.t.p, 1 mole of any gas occupies $22.4\ dm^3$. From the equation, 1 mole of $O_2$ is produced from 2 moles of $H_2O_2$.
The molar mass of $H_2O_2$ is $M=(2	imes1.0 + 2	imes16.0)=34\ g/mol$.
## Step2: Calculate the mass of $H_2O_2$
Since 1 mole of $O_2$ (22.4 $dm^3$ at s.t.p) is produced from 2 moles of $H_2O_2$, and 2 moles of $H_2O_2$ have a mass of $m = 2	imes34\ g=68\ g$.
# Answer: D. 68 g

### 26.
# Explanation:
## Step1: Recall metal extraction methods
Gold is usually extracted by methods like cyanidation. Copper is extracted by smelting. Iron is extracted by reduction in a blast - furnace. Sodium is a highly reactive metal and is extracted by electrolysis of its molten salts (e.g., molten sodium chloride).
## Step2: Choose the answer
Sodium is extracted by electrolysis.
# Answer: D. Sodium

### 27.
# Explanation:
## Step1: Recall the polymerization of ethyne
The polymerization of ethyne gives benzene. The reaction is $3C_2H_2
ightarrow C_6H_6$.
## Step2: Select the answer
Polymerization of ethyne gives benzene.
# Answer: A. benzene

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QUESTION IMAGE

Question

Explanation:

20.

Step1: Recall diatomic gases

Step2: Identify the answer

Step1: Understand carbon(II) oxide toxicity

Step2: Select the answer

Step1: Analyze alkene reactivity

Step2: Choose the answer

Answer:

21.