Question
A solid has a melting point of 1582 °C and does not dissolve in water. It does not conduct electricity in the molten state. What type of structure does the solid have?
A. Ionic
B. Metallic
C. Giant molecular
D. Simple molecular
▶️Answer/Explanation
C
Since it does not dissolve in water and it does not conduct electricity in the molten state, it is not an ionic structure compound.
Which means it is a covalent structure compound and as it also has a high melting point, it is a giant molecular covalent compound.
Question
What is the difference between the strength and the length of the carbon-oxygen bond in butanal and in butan-1-ol?
A. The bond in butanal is stronger and longer than in butan-1-ol.
B. The bond in butanal is weaker and shorter than in butan-1-ol.
C. The bond in butanal is weaker and longer than in butan-1-ol.
D. The bond in butanal is stronger and shorter than in butan-1-ol.
▶️Answer/Explanation
D
The butanal name suggests that it contains four carbon atoms having the root word of but-. The suffix -al suggests that the functional group aldehyde is present in it. Which means it has C=O (double bond )in it.
Butan-1-ol is a primary alcohol that is butane in which a hydrogen of one of the methyl groups is substituted by a hydroxy group. Here, C-O single bond exists.
Single bond is weaker and smaller than double bond. Hence, bond in butanal is stronger and shorter than in butan-1-ol.
Question
Which sequence has the molecules in order of increasing nitrogen-nitrogen bond length?
A. \({{\text{N}}_{\text{2}}} < {{\text{N}}_{\text{2}}}{{\text{H}}_{\text{4}}} < {{\text{N}}_{\text{2}}}{{\text{H}}_{\text{2}}}\)
B. \({{\text{N}}_{\text{2}}} < {{\text{N}}_{\text{2}}}{{\text{H}}_{\text{2}}} < {{\text{N}}_{\text{2}}}{{\text{H}}_{\text{4}}}\)
C. \({{\text{N}}_{\text{2}}}{{\text{H}}_{\text{4}}} < {{\text{N}}_{\text{2}}}{{\text{H}}_{\text{2}}} < {{\text{N}}_{\text{2}}}\)
D. \({{\text{N}}_{\text{2}}}{{\text{H}}_{\text{2}}} < {{\text{N}}_{\text{2}}}{{\text{H}}_{\text{4}}} < {{\text{N}}_{\text{2}}}\)
▶️Answer/Explanation
B
Hence, increasing nitrogen-nitrogen bond length is: \({{\text{N}}_{\text{2}}} < {{\text{N}}_{\text{2}}}{{\text{H}}_{\text{2}}} < {{\text{N}}_{\text{2}}}{{\text{H}}_{\text{4}}}\).
Question
Which substance has the following properties?
• Low melting point
• Very soluble in water
• Does not conduct electricity when molten
A. Glucose, \({{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}\)
B. Silicon dioxide, \({\text{Si}}{{\text{O}}_{\text{2}}}\)
C. Sodium chloride, NaCl
D. Tetrachloromethane, \({\text{CC}}{{\text{l}}_{\text{4}}}\)
▶️Answer/Explanation
A
Silicon dioxide has very high melting point. Sodium chloride conduct electricity when molten. CCl4 is not very soluble in water.
The given compound is Glucose.
Question
How many electrons form the carbon–oxygen bond in methanal, HCHO?
A. 2
B. 4
C. 8
D. 12
▶️Answer/Explanation
B
It has a C=O bond i.e. 4 electrons form this bond.