Which of the following is a common laboratory indicator for bases?
Methyl orange
Phenolphthalein
Bromothymol blue
Litmus
Correct answer is B
Phenolphthalein is a common laboratory indicator used to detect the presence of bases in a solution. In its basic form (pH > 8.3), it turns pink or purple, indicating the presence of a base.
What is the maximum number of electrons that can occupy the second energy level (n=2)?
2 electrons
18 electrons
8 electrons
32 electrons
Correct answer is C
The correct answer is (b). The second energy level (n=2) can hold a maximum of 8 electrons. It consists of two subshells, 2s and 2p, which can hold 2 and 6 electrons, respectively.
Which of the following statements is true for strong electrolytes?
They do not conduct electricity in the molten state
They completely dissociate into ions in solution
They are non-polar substances
They partially dissociate into ions in solution
Correct answer is B
They completely dissociate into ions in solution. Strong electrolytes are substances that fully dissociate into ions when dissolved in water or melted. As a result, they produce a high concentration of ions in the solution, allowing for efficient electrical conductivity.
24
16
8
32
Correct answer is C
The atomic number of an element is equal to the number of protons, which in this case is 8. The mass number is the total number of protons and neutrons, which is 16. To find the number of neutrons, we subtract the atomic number from the mass number:
Number of neutrons = Mass number - Atomic number
Number of neutrons = 16 - 8
Number of neutrons = 8
So, the element has 8 neutrons.
The boiling point is always higher than the melting point
The melting point is always higher than the boiling point
The melting and boiling points are always the same for all substances
The melting and boiling points can vary depending on the substance
Correct answer is D
The melting and boiling points are specific physical properties of each substance and can vary depending on the nature of the substance. Different substances have different melting and boiling points, which are determined by the strength of the intermolecular forces and the molecular structure of the substance.
What is the IUPAC name for the compound CCl\(_4\)?
Tetrahydrochloride
Tetrachloromethane
Carbon tetrachloride
Chloroform
Correct answer is B
The compound CCl\(_4\) is a chlorinated hydrocarbon with a central carbon atom and four chlorine atoms attached to it. According to IUPAC rules, the correct name for this compound is "tetrachloromethane."
The lanthanides and actinides are located in which block of the periodic table?
P-block
S-block
F-block
D-block
Correct answer is C
The lanthanides and actinides are located in the f-block of the periodic table, which is a separate row placed at the bottom of the main table. These elements are also known as the inner transition metals.
Which of the following is a characteristic property of acids?
Turn litmus paper blue
Bitter taste
pH value above 7
React with metals to produce hydrogen gas
Correct answer is D
Acids are substances that can donate protons (H+) in aqueous solutions. When acids react with certain metals, they can release hydrogen gas (H2) as one of the products. This is a common behavior of many acids and can be used to distinguish them from other substances.
Which of the following is an example of a primary cell?
Alkaline battery
Nickel-cadmium battery
Lead-acid battery
Lithium-ion battery
Correct answer is A
Primary cells are non-rechargeable batteries, and the alkaline battery is a common example of a primary cell
The process of rusting is an example of the formation of
Basic oxide
Acidic oxide
Reducing oxide
Amphoteric oxide
Correct answer is A
Rusting is the corrosion of iron or steel due to exposure to oxygen and moisture in the air, resulting in the formation of iron oxide (Fe\(_2\)O\(_3\) or Fe\(_3\)O\(_4\)), which is an example of an acidic oxide.
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