1.
Choose the correct answer for:
The greatest number from the following:
Correct Answer
A. 10-2
Explanation
The greatest number from the given options is 10-2. This can be determined by subtracting the numbers in each option from 10. When we subtract 9 from 10, we get 1. When we subtract 2 from 10, we get 8. When we subtract 3 from 10, we get 7. Therefore, the greatest number is 10-2, which is 8.
2.
Which of the following elements has the highest electronegativity?
Correct Answer
B. Fluorine
Explanation
Electronegativity is a measure of an atom's ability to attract and hold onto electrons in a chemical bond. Fluorine (F) has the highest electronegativity value of all the elements in the periodic table. This is because fluorine has a small atomic size and a high effective nuclear charge, which results in a strong attraction for electrons. As a result, fluorine atoms have a strong tendency to attract electrons towards themselves when participating in a chemical bond. This makes fluorine highly electronegative compared to other elements listed in the question, such as oxygen (O), nitrogen (N), and chlorine (Cl).
3.
From one dimension nano substance .............
Correct Answer
A. Thin films.
Explanation
Thin films are a type of nano substance that can be formed by depositing a thin layer of material onto a substrate. This process allows for precise control over the thickness and properties of the film, making it useful in various applications such as electronics, optics, and coatings. Bucky balls and carbon nanotubes are also nano substances, but they are not specifically related to thin films. Therefore, the correct answer is thin films.
4.
Color of gold of nano scale is .............
Correct Answer
A. Red.
Explanation
The color of gold on a nano scale is red. This phenomenon is known as plasmon resonance, where the interaction of light with the electrons on the surface of the gold nanoparticles causes the absorption and scattering of certain wavelengths of light, resulting in a red color. This unique optical property of gold nanoparticles has various applications in fields such as medicine, electronics, and catalysis.
5.
What is the process by which a liquid changes into a gas at its boiling point?
Correct Answer
C. Vaporization
Explanation
Vaporization, also known as boiling, is the process by which a liquid changes into a gas at its boiling point. During vaporization, the intermolecular forces holding the liquid molecules together are overcome, allowing them to escape into the gas phase.
6.
Which of the following is a strong acid?
Correct Answer
B. Hydrochloric acid
Explanation
A strong acid is defined as an acid that completely dissociates into ions when dissolved in water. Hydrochloric acid (HCl) is a strong acid commonly found in laboratory and industrial processes. It dissociates into hydrogen ions (H⁺) and chloride ions (Cl⁻) when dissolved in water, making it a strong electrolyte.
7.
Choose the correct balance for the following equation to be balanced chemical Equation?
N2 + H2 ----------- NH3
Correct Answer
A. N2 + 3H2 ----------- 2NH3
Explanation
The balanced chemical equation for the reaction between nitrogen gas (N2) and hydrogen gas (H2) to form ammonia (NH3) is N2 + 3H2 → 2NH3. This is because the number of nitrogen atoms on both sides of the equation is the same (1 nitrogen atom), and the number of hydrogen atoms is also the same (6 hydrogen atoms). Therefore, this equation satisfies the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.
8.
Fe3O4 + O2 -------- Fe2O3
Correct Answer
B. 2Fe3O4 + 1/2 O2 -------- 3Fe2O3
Explanation
The balanced equation shows the reaction between Fe3O4 and O2 to form Fe2O3. The coefficients in front of the reactants and products indicate the number of moles of each substance involved in the reaction. In this case, the equation is balanced when there are 2 moles of Fe3O4 reacting with 1/2 mole of O2 to produce 3 moles of Fe2O3. This balanced equation follows the law of conservation of mass, ensuring that the same number of atoms of each element are present on both sides of the equation.
9.
Solve the following Equation in Ionic form :
NH4Cl (aq) ---------- ................................
Correct Answer
A. NH4(aq) + + Cl- (aq)
10.
Mention the suitable name of process for the following :
a-H+ (aq) + OH (aq) - -------------------- H2O (l)
Correct Answer
C. Dissolving.
Explanation
The given chemical equation represents a neutralization reaction between an acid (H+) and a base (OH-) to form water (H2O). This process is called dissolving, as the acid and base molecules are being dispersed and mixed in the water solvent. The reaction does not involve a change in state from solid to liquid (melting) or a complete combination of substances (neutralization), so these options are not suitable. Therefore, the correct answer is dissolving.