The extraction of aluminium is done by: MCQ with Answer and Explanation

Explanation:
Ethane: H₃C-CH₃. There is one C-C single bond and six C-H single bonds, total 7 covalent bonds. Each bond is a sigma bond. The structural formula shows 7 bonds. Methane has 4, propane 10. Counting bonds is simple: each line represents a covalent bond.

Explanation:
Neutron has mass approximately equal to proton (1.675 × 10⁻²⁷ kg) and no electric charge. Proton mass ~1.673 × 10⁻²⁷ kg, positive charge. Electron mass ~9.11 × 10⁻³¹ kg, negative charge. Positron is the antiparticle of electron, same mass, positive charge. Neutron's neutrality makes it important for nuclear stability.

Explanation:
Ionization energy generally increases across a period due to increasing nuclear charge and decreasing atomic size. Among Na, Mg, Al, and Si (Period 3), Si has the highest effective nuclear charge and smallest size, thus requiring the maximum energy to remove the outermost electron from its gaseous state.