Category: Chemistry Mcqs

Which one has no charge?

A. Atoms
B. Molecule
C. H2O
D. Compounds

Answer

Correct Answer: A. Atoms

Detail about MCQs

The correct answer is: A. Atoms
An atom in its natural state has no overall charge because the number of positively charged protons in the nucleus is equal to the number of negatively charged electrons orbiting it. This balance makes it electrically neutral.
Other options, like molecules (e.g., H₂O), can sometimes have partial charges due to polar bonds, and compounds may also form ions.

Which element is found at the center of the periodic table?

A. Hydrogen
B. Helium
C. Carbon
D. Iron

MCQs Taken from BPSC CSS 2024, Tehsildar Paper

Answer

Correct Answer: D. Iron

Detail about MCQs

The periodic table does not have a central element in a strict geometric sense, as it is organized based on atomic number, electron configuration, and recurring chemical properties. However, iron (Fe) is commonly associated with the “center” in a metaphorical sense because it is near the middle of the periodic table, specifically in the transition metals group (Group 8, Period 4).
Answer: D. Iron

Which one of these scientists formulated basic laws of Geometry?

A. Pythagoras
B. Archimedes
C. Aristotle
D. None of these

Answer

Correct Answer: A. Pythagoras

Detail about MCQs

Pythagoras is famously associated with the Pythagorean Theorem, which is a fundamental principle in geometry. While he may not have formulated all basic laws of geometry, his work significantly influenced the development of geometric principles.

In conversion of acid halides to ester, pyridine is used to?

A. Stabilize Acid Halides
B. Consume HCl formed in the reaction
C. Dehydrate Alcohol
D. None of these

Answer

Correct Answer: B. Consume HCl formed in the reaction

Detail about MCQs

In the conversion of acid halides to esters, pyridine is often used to: Consume HCl formed in the reaction Pyridine is a base and can neutralize the hydrochloric acid (HCl) that is generated as a byproduct in the reaction between acid halides and alcohols to form esters. This helps shift the equilibrium of the reaction toward the formation of the ester by removing the acidic byproduct.

Propylene glycol and trimethylene glycol are?

A. Functional Group Isomers
B. Metamers
C. Position Isomers
D. Tautomers

Answer

Correct Answer: B. Metamers

Detail about MCQs

Metamers are a type of constitutional isomerism where the connectivity of atoms in the molecules is the same, but the arrangement of atoms along the carbon chain differs. Propylene glycol and trimethylene glycol have the same molecular formula (C3H8O2), but the arrangement of carbon atoms differs, leading to different chemical properties.

When phenol reacts with excess of bromine in aqueous solution it reacts in the formation of?

A. Ortho/para Bromophenol
B. Meta bromophenol
C. 2,4,5-Tribromophenol
D. 3,5-O bromophenol

Answer

Correct Answer: C. 2,4,5-Tribromophenol

Detail about MCQs

When phenol reacts with an excess of bromine in an aqueous solution, it forms: 2,4,5-Tribromophenol
The excess bromine can lead to multiple bromination reactions on the aromatic ring, resulting in the substitution of three bromine atoms at the 2nd, 4th, and 5th positions of the phenol ring. This compound is known as 2,4,5-tribromophenol.

Identify the electrophile called as acylium ion?

A. R3N+
B. RCO+
C. RCOO+
D. RNO+

Answer

Correct Answer: B. RCO+

Detail about MCQs

The acylium ion is a cationic species with a positive charge on the carbon atom of the carbonyl group (CO). It is a reactive intermediate often involved in acylation reactions, where it acts as an electrophile by accepting a pair of electrons during a chemical reaction. This is commonly seen in organic chemistry reactions involving acyl halides, anhydrides, or other acylating agents.

Consider the reaction below, if 5 moles each of hydrogen and oxygen are reacted to form water, the reaction reveals? 2H2 + O2 __> 2H2O

A. H2 is excess reagent
B. O2 is limiting reagent
C. H2 is limiting reagent
D. Reaction has no limiting reagent

Answer

Correct Answer: D. Reaction has no limiting reagent

Detail about MCQs

To determine which reactant is the limiting reagent and which is in excess, we need to compare the mole ratios of hydrogen (H2) and oxygen (O2) in the balanced chemical equation to the actual moles of each reactant given:
Balanced equation: 2H2 + O2 → 2H2O
From the balanced equation, we can see that the stoichiometric ratio of H2 to O2 is 2:1.
Now, you have 5 moles each of hydrogen and oxygen:
• Moles of H2 = 5 moles
• Moles of O2 = 5 moles The mole ratio of H2 to O2 in the given reactants is 5:5, which simplifies to 1:1. Since the actual ratio of moles (1:1) matches the stoichiometric ratio (2:1) in the balanced equation, it means that there are enough moles of both hydrogen and oxygen to react completely without either being in excess or limiting. Therefore, the correct answer is:

When aqueous solution of NaCl is electrolysed?

A. Cl2 is evolved at the cathode
B. H2 is evolved at cathode
C. Na is deposited at the cathode
D. Na appears at the nodes

Answer

Correct Answer: B. H2 is evolved at cathode

Detail about MCQs

Electrolysis of NaCl (sodium chloride) is a chemical process in which an electric current is passed through an aqueous (water-based) solution of sodium chloride. During this process, the compound NaCl is broken down into its constituent elements through redox reactions at the electrodes.

At the cathode (negative electrode), water (H2O) molecules are reduced by gaining electrons to form hydrogen gas (H2): 2H2O + 2e- -> H2(g) + 2OH-

At the anode (positive electrode), chloride ions (Cl-) are oxidized to form chlorine gas (Cl2): 2Cl- -> Cl2(g) + 2e-

So, electrolysis of NaCl in aqueous solution results in the production of hydrogen gas at the cathode and chlorine gas at the anode. This process is used in various industrial applications and plays a role in the production of chemicals like sodium hydroxide and chlorine gas.

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