Explanation

Use the Gibbs free energy equation:

$$\Delta G=\Delta H-T\Delta S$$

For a process to be spontaneous, $Delta G < 0$

• If $Delta H < 0$ (exothermic)

• And $Delta S > 0$ (entropy increases)

• Then:

  $$\Delta G=\text{negative}-T\times \text{positive}=\text{always negative}$$

 So, no matter the temperature, $Delta G$ will be negative ⇒ spontaneous at all temperatures

Explanation

• A Decomposition Reaction is a type of chemical reaction where a single compound breaks down into two or more simpler substances.
• This is the opposite of a Combination Reaction, where two or more substances combine to form a new compound.

Explanation

• A release of gas is typically a sign of a chemical change, not a physical change.

The signs of physical change:

• Change that can be reversed
• The substance does not turn into a new substance

Explanation

• About 97.5% of the water on Earth is saltwater, found in oceans, seas, and salt lakes.
• The remaining 2.5% is freshwater, found in rivers, lakes, wetlands, and underground aquifers.

Explanation

Kaolin, or 'china clay' as it is commonly called, is a hydrated aluminum silicate crystalline mineral

Kaolinite is a clay mineral, with the chemical composition: Al2Si2O5(OH)4.

It is a layered silicate mineral, with one tetrahedral sheet of silica ( SiO 4) linked through oxygen atoms to one octahedral sheet of alumina ( AlO 6).

Explanation

Remember that water has 2 lone pairs on oxygen.

Hence, according to VSEPR theory, the water molecule arrives at a bent or a V-shape

Due to the presence of lone pair-lone pair, lone pair-bond pair and bond pair-bond pair repulsions

Explanation

• Magnesium (Mg) is an element, not a compound.
• It is a pure substance made up of only one type of atom.
• Whereas compounds are made up of two or more different elements.

Examples of compounds:

• Water (H2O) - Compound of Hydrogen and Oxygen
• Common salt (NaCl) - Compound of Sodium and Chlorine
• Washing soda (Na2CO3) - Compound of Sodium, Carbon, and Oxygen
• Carbon dioxide (CO2) - Compound of Carbon and Oxygen
  
• Sugar (C6H12O6) - Compound of Carbon, Hydrogen, and Oxygen

Explanation

• Liquids have a fixed volume, but their shape changes depending on the container they are in.
• As their particles are close together but free to move past each other.

Explanation

• Volume is the amount of space a material object occupies.
• It is a measure of the amount of three-dimensional space occupied by a substance or object.
• It is typically measured in units such as cubic meters (m³), cubic centimeters (cm³), or liters (L).

Explanation

The percentage by mass of an element in a compound is calculated using the formula:

Percentage by mass = (Mass of element in 1 mole of compound / Molar mass of compound) x 100