Assertion (A): Hydrogen is a better fuel than CNG. Reason (R): Hydrogen is highly explosive and difficult to store safely. MCQ with Answer and Explanation

Explanation:
John Dalton put forward the atomic theory in 1808, proposing that matter is made of indivisible atoms, atoms of same element are identical, and compounds are combinations of atoms. Electron was discovered by J.J. Thomson, periodic table by Mendeleev, neutron by Chadwick.

Explanation:
Ammonium chloride (NH4Cl) consists of the ammonium ion (NH4+) and the chloride ion (Cl-). The bond between NH4+ and Cl- is ionic. However, within the ammonium ion itself, the nitrogen atom is bonded to four hydrogen atoms via covalent bonds (three normal and one coordinate). Thus, it contains both.

Explanation:
In diamond, each carbon is sp³ hybridized and forms four covalent bonds, using all valence electrons. There are no delocalized electrons; thus it cannot conduct electricity. Graphite, with sp² hybridization, has one delocalized electron per carbon, making it a conductor. Diamond is an electrical insulator but excellent thermal conductor.