The correct answer is 2 Proton and 2 Neutron.

Key Points

• Alpha particle is alternatively known as Alpha radiation or Alpha ray.
• It is a positively charged particle emitted from the decay of various radioactive materials.
• Alpha particle mass is due to the two protons and two neutrons bonding. Hence option 2 is correct.
• Thus, the Alpha ray nucleus is very similar to the Helium-4 nucleus.
• It is represented by the Greek alphabet α.
• Alpha particles are generally produced during standard radioactive decay.
• The mass of an alpha particle is αm = 6.644657230(82) × 10^-27 Kg

Concept:

• A strong acid is an acid that is completely ionized in water to produce hydronium ions. The conjugate base of the acid is very weak as it does not react with water at all.
• A strong base is an acid that is completely ionized in water to produce OH-. The conjugate acid is very weak as it does not react with water at all.
• A weak acid and base is an acid that partially reacts with water to produce hydronium and hydroxide ions respectively and the conjugate base and conjugate base and acid both are weak.

Explanation:

• Phenolphthalein is an acid-base indicator and it changes color in pH ranges between 8.3 to 10. In acidic solution, it appears colorless and in basic solution, it turns pink in color.
• In test tube A throughout the acid-base titration, the solution remains colorless after adding phenolphthalein. Thus, it is a strong acid.
• In test tube B, first, the solution remains colorless but after adding pink colorless, then the solution becomes pink. Thus, it is a weak acid.
• In test tube C, the solution become pink after adding the phenolphthalein indicator. Thus, it is a strong base.

Therefore, from the above discussion, it is clear that the correct answer is A = Strong Acid B = Weak Acid C = Strong Base.

The correct answer is h.

Key Points

• Nettles are covered with tiny hollow hair. These cause intense pain when touched.
• Stinging happens because of presence of-
  • Formic acid
  • Histamine
  • Oxalic acid
• The pain caused by nettle sting can be reduced by antihistamines which neutralizes the effect of histamine present in the nettle and caused inflammation and pain.

Additional Information

• Sulfuric acid (H₂SO₄) is also called oil of vitriol, or hydrogen sulfate.
  • It is viscous, colorless and corrosive liquid.
  • It has high affinity for water.
  • Its pH is 1.87 - highly acidic.
• Properties of acids-
  • They are sour in taste and are soluble in water.
  • They have corrosive action.
  • Aqueous solution of acid conduct electricity.
  • It turns blue litmus red.
  • Acid react with metals to release Hydrogen gas.
  • Acids react with bases and produces salt.

The correct answer is 1) Both A and R are true, and R is the correct explanation of A.

Concepts:-

The pH scale is used to measure the acidity or basicity of an aqueous solution. It ranges from 0 to 14, with 7 being neutral. A pH less than 7 indicates an acidic solution, while a pH greater than 7 indicates a basic solution. The pH of a solution is inversely related to the concentration of hydrogen ions (H+) it contains; a higher concentration of H+ ions results in a lower pH, and vice versa.

Explanation:-

• Assertion (A): Diluting an acid solution with water decreases its H+ ion concentration. Because pH is inversely related to the concentration of H+ ions, diluting the acid (thereby reducing the concentration of H+ ions) results in an increase in the pH of the solution. This makes the solution less acidic.
• Reason (R): The concentration of H+ ions directly determines the acidity of a solution. Dilution decreases the number of H+ ions per unit volume, which directly results in an increase in the pH level of the solution. This is because the pH scale is logarithmic, so even a small decrease in H+ concentration can have a significant impact on the pH value.

Key Concepts for Understanding the Impact of Dilution on pH:

• Logarithmic Nature of the pH Scale: The pH scale is logarithmic, meaning each unit change in pH represents a tenfold change in the concentration of H+ ions. This explains why diluting an acid can significantly increase its pH.
• Impact of Dilution on Acidity: Dilution is a common method used to reduce the acidity of a solution for various applications, by increasing its pH through the reduction of H+ ion concentration.
• Chemical Equilibrium: In some cases, diluting an acid can also shift the chemical equilibrium of any ionizable molecules present, potentially further affecting the pH.

Conclusion:-

So, The correct statement is Both A and R are true, and R is the correct explanation of A

The correct answer is The brown deposit on the blade is copper.

Explanation:

• Colour of the solution from blue to green is due to the formation of iron sulphate, a new substance. The brown deposit on the iron nail is copper, another new substance. We can write the reaction as:

Copper sulphate solution (blue) + Iron → Iron sulphate solution (green) + Copper (brown deposit)

• When an iron nail is dipped in copper sulphate solution, a brown copper coating forms on the surface of the iron, and the colour of the copper sulphate solution changes from blue to green.
• Because it displaces copper from the copper sulphate solution, the reaction shows that iron is more reactive than copper.
• The iron enters the solution as Fe (II) and forms the ferrous sulphate solution.

Explanation:

• The blue colour of copper sulfate crystals available in the market is due to water of crystallization.
• The term "water of crystallization" refers to water molecules that are integrated into the crystal structure of a compound.
• When copper sulfate forms its crystals, it incorporates five molecules of water into the structure.
• This hydrated form of copper sulfate is represented as CuSO₄·5H₂O, and it's commonly known as blue vitriol or bluestone.
• When you heat copper sulfate pentahydrate (CuSO₄·5H₂O), the heat energy causes the water molecules to evaporate, and the compound becomes anhydrous copper sulfate, represented as CuSO₄.
• The loss of water of crystallization turns the blue crystals into a white powder.

Therefore, it's the water of crystallization (water molecules) that's responsible for the blue color of the copper sulfate crystals. If the water is removed, the compound becomes white.

The correct answer is Boyle’s law.

Key Points

• Boyle's Law states that at a constant temperature, the pressure of a fixed amount of gas varies inversely with its volume.
• This means that as the volume of a gas decreases, its pressure increases, provided the temperature remains constant, and vice versa.
• The mathematical expression for Boyle’s Law is P ∝ 1/V or P1V1 = P2V2, where P is pressure and V is volume.
• Robert Boyle discovered this law in the 17th century.
• Boyle's Law is a fundamental principle in the study of gases and is crucial for understanding gas behavior under varying pressure and volume conditions.
• This law is applied in various real-world scenarios, such as in breathing mechanisms and in the functioning of syringes and hydraulic systems.

Additional Information

• Dalton’s Law
  • Dalton's Law, also known as the Law of Partial Pressures, states that in a mixture of non-reacting gases, the total pressure is equal to the sum of the partial pressures of individual gases.
  • This law is essential for understanding gas mixtures and is widely used in fields such as chemistry and meteorology.
• Avogadro’s Law
  • Avogadro's Law states that equal volumes of all gases, at the same temperature and pressure, contain an equal number of molecules.
  • This principle is fundamental in determining the relationships between volume, temperature, and number of molecules in gases.
• Charles’s Law
  • Charles's Law states that the volume of a fixed amount of gas is directly proportional to its absolute temperature, provided the pressure remains constant.
  • This law explains how gases expand when heated and is crucial in applications involving temperature changes in gases.

Concept:

• The Law of conservation of mass states that matter can neither be created nor destroyed.
• In a chemical reaction, new compounds different from the starting materials are formed.
• In accordance with the law of conservation of mass, thus the number of atoms of each element in the reactant and product side will be same.

So, we need to balance the chemical equation.

Calculation:

To balance a chemical reaction:

• Check the number of atoms before and after the reaction.
• Balance the elements one at a time by adding coefficients before them.
• Change the coefficients as required.
• Never change the subscripts.
• The reaction given is:

P₄ + NaOH + H₂O → NaH₂PO₂ + PH₃

Let us balance the elements:

Thus, the equation becomes:

P₄ + 3NaOH + 3H₂O → 3NaH₂PO₂ + PH₃

At this stage, everything is balanced.

Hence, the number of moles of NaOH, H₂O and NaH₂PO₂ respectively are 3, 3, 3.

The correct answer is 18.

Concept:

• Atomic number: The number of electrons or protons in an atom.
• Mass number: The number of protons and neutrons taken together.
• Isotopes: The elements with the same atomic number but different mass numbers due to the different numbers of neutrons.

Explanation:

Group number: It tells how many valence electrons are present in the outermost shell of the atom.

• Element X has group number 15. So, the no. of valence electrons is 15-10 = 5.

Period number: It tells how many shells are there in the atom. 

• Element X belongs to the 3rd period. So, there are 3 shells. 

Electronic configuration of Element X = 2, 8, 5.

Its atomic number is 15. Therefore, there are 15 electrons and 15 protons in it. 

The mass number of its isotope is 33.

No. of neutons + no. of protons = 33

No. of neutons + 15 = 33

No. of neutrons = 33 - 15 = 18

Key Points

• Nitric acid (HNO₃), also known as aqua fortis, derived from Latin for "strong water," is a potent and corrosive mineral acid renowned for its reactivity with various metals, including silver. It is colorless and fuming in nature.
• Primarily, nitric acid finds extensive application in the production of fertilizers and explosives.
• Approximately 80% of its usage is attributed to fertilizer production, with a minor portion allocated to explosive manufacturing.
• Additionally, nitric acid is referred to as spirit of niter. Notably, accidental exposure to nitric acid can pose severe health risks, and in some cases, it can be fatal.

Important Points

• Formic acid, with the chemical formula HCOOH and molecular structure H−C−O−H, is recognized as the simplest carboxylic acid. It occurs naturally in certain ant species and is found in the venom of bee and ant stings.
• Chloric acid, represented by the chemical formula HClO₃, is a colorless liquid known for its strong acidic and oxidizing properties. It serves as a precursor to chlorate salts.
• Hydrobromic acid presents as a colorless to light yellow liquid characterized by its highly acidic and corrosive nature. It is classified as a strong mineral acid, formed by dissolving hydrogen bromide in water.