Explanation

• The nucleus of an atom contains protons and neutrons.
• The nucleus is the central part of an atom.
• Protons have a positive charge.
• Neutrons have no electric charge.
• Electrons are found outside the nucleus
• The nucleus makes up much less than. 01% of the volume of the atom,
• But typically contains more than 99.9% of the mass of the atom.

Explanation

• The atomic mass of carbon is defined as 12.01 amu (atomic mass unit).
• Molar mass: 12.011 g/mol
• Carbon-12 isotope: Exactly 12 amu

Explanation

Given

a : b = 2 : 3

b : c = 3 : 4

Step 1: Compare the common term(b)

Both ratios have (b=3), so they can be combined directly:

a : b : c = 2 : 3 : 4

Explanation

Materials are classified based on how they conduct heat.

- Conductors: Allow heat to pass through easily (e.g., metals like copper, iron).

- Insulators: Do not allow heat to flow through easily.

- Examples of insulators: Wood, plastic, rubber, glass.

- Used in cooking handles, thermal flasks, and electrical wire coatings.

Explanation

Paper chromatography.

• Most common and simplest technique
• Needs minimal equipment
• Easy to perform
• Uses paper as the stationary phase and solvent as the mobile phase
• Separates components by their affinity for the two phases

Explanation

• The number of moles is directly proportional to the mass of an element.
• It is calculated by dividing the mass of the element by its molar mass.
• Mass: As the mass increases, the number of moles increases by the same factor (n = mass/molar mass).
• Number of Atoms: As the number of atoms increases, the number of moles increases according to Avogadro's number.

Explanation

• As you move left to right across a period, electronegativity increases.
• Nuclear charge increases — more protons pull more strongly on bonding electrons
• Atomic radius decreases — electrons are held closer to the nucleus
• Shielding stays roughly the same (electrons are added to the same shell), so the effective nuclear charge rises

Explanation

A centrifuge is a machine that uses centrifugal force to separate particles of different densities or sizes from a mixture.

It is commonly used to separate:

• Liquids from solids (e.g., mud, sludge)
• Heavy particles from lighter particles (e.g., sedimentation)
• Immiscible liquids (e.g., oil and water)

Explanation

Temporary hardness is caused by:

• Calcium bicarbonate — Ca(HCO₃)₂
• Magnesium bicarbonate — Mg(HCO₃)₂
• Release Ca²⁺ and Mg²⁺ in water.
• Removed by boiling → form insoluble CaCO₃, MgCO₃.
• Permanent hardness (sulfates/chlorides) can't be removed by boiling.

Explanation

Important: Simply adding more product does not permanently increase Kc; it changes the reaction quotient until equilibrium is restored.

• Kc is the equilibrium constant.
• A larger Kc generally indicates equilibrium favors products.
• At equilibrium, the value of Kc depends on temperature.
• A catalyst does not change Kc.