Tag: science & technology

Alkali metals (Group 1 elements like Li, Na, K) have one electron in their outermost shell. This single valence electron makes them highly reactive as they readily lose it to form +1 ions.

Alkali metals have LOW densities compared to most other metals. Lithium, sodium, and potassium are so light they can float on water. The density increases down the group, but they remain relatively low-density metals overall.

As atomic number increases down Group 1, melting and boiling points DECREASE. This is because metallic bonding weakens as atomic size increases - larger atoms have lower charge density and weaker attraction to delocalized electrons.

Diamonds are pure carbon arranged in a crystal lattice structure. Each carbon atom forms four strong covalent bonds with neighboring carbons, creating diamond's legendary hardness. Hydrogen, gallium (option C has typo 'Galium'), and boron form different structures entirely.

Helium is chemically inert and non-flammable, so smoking doesn't pose a combustion risk around it. The question likely confuses helium with other gases or refers to inappropriate contexts like inhalation hazards. A 'no smoking' sign around helium storage makes no scientific sense.

The conversion formula is F = (C × 9/5) + 32. For 100°C: (100 × 9/5) + 32 = 180 + 32 = 212°F. Option C is the Kelvin equivalent (373K), and options A and D are incorrect conversions.

Water's formula is H2O, meaning 2 hydrogen atoms and 1 oxygen atom, totaling 3 atoms per molecule. Option A incorrectly counts only hydrogen, B is too few, and C is too many.

Robert Boyle is widely regarded as the father of modern chemistry for his pioneering work on gas laws (Boyle's Law) and his advocacy of the scientific method in chemical research. He published 'The Sceptical Chymist' in 1661, which helped establish chemistry as a quantitative science. Kelvin (William Thomson) worked in thermodynamics, Archimedes was an ancient mathematician and physicist, and Aristotle was a philosopher whose natural philosophy predated modern chemistry.