General Science GK Questions with Answers – Page 58

Helium is a noble gas whose atoms exist singly, so it is a monatomic gas, not a diatomic one. Helium has a completely filled first shell (1s²), so its atoms have no tendency to share electrons or bond with each other.

Quartz is silicon dioxide (SiO 2 ), so it contains silicon and oxygen. Quartz is one of the most common minerals in the Earth's crust and the main part of sand.

Root hairs are thin outgrowths of the root's epidermal cells that greatly increase the area for absorbing water and minerals.

A shoot growing towards the light is moving in the direction of the stimulus, which makes it a positive tropism.

Both are cnidarians, simple aquatic animals with stinging cells. Members of phylum Coelenterata (Cnidaria) have radial symmetry, two body layers, a single opening that works as both mouth and anus, and stinging cells called cnidoblasts on their tentacles, used to catch prey and for defence.

The Himalayan nettle yields a strong natural fibre that can be spun and woven into cloth. Girardinia diversifolia, known as Himalayan giant nettle or allo, is a stinging shrub that grows wild in the moist forests of the Himalayas, including Uttarakhand, Himachal Pradesh and the North-east, as well as Nepal.

Plant cells have a cellulose wall and one large central vacuole, but they do have a plasma membrane, just like animal cells.

Zika is spread mainly by the Aedes mosquito that also carries dengue, and it can pass between sexual partners. The Zika virus is a flavivirus first identified in Uganda's Zika forest in 1947.

The vaccine protects against several pneumococcal diseases and so cuts antibiotic use, but no vaccine is free of side effects.

Bleaching powder is an oxidising agent, not a reducing agent, so this statement is the false one. Bleaching powder, calcium oxychloride (CaOCl₂), is made by passing chlorine gas over dry slaked lime, Ca(OH)₂.

The ball keeps slowing down by about 9.8 m/s every second until its speed becomes zero at the top, which takes 40 ÷ 9.8 ≈ 4 seconds.

On heating, silver oxide breaks down into silver metal and oxygen, while zinc oxide and magnesium oxide stay unchanged. The reaction is 2Ag₂O → 4Ag + O₂.

Sexual reproduction mixes the genes of two parents, so the young differ from each other and from their parents, and variation helps a species survive changing conditions.

Pulling the hands back stretches the time in which the ball stops, so its deceleration and the force on the hands become smaller.

Vision is caused by the electric field of light acting on the light-sensitive molecules of the retina. Light is an electromagnetic wave in which electric and magnetic fields oscillate at right angles to each other and to the direction of travel.

Among the alkali metals, reactivity with water increases down the group, so lithium, at the top, is the least reactive.

Washing soda is sodium carbonate decahydrate, sodium carbonate with ten molecules of water of crystallisation.

The energy gained is the charge of the electron multiplied by the potential difference it crosses. Energy W = qV.

The statement is Kirchhoff's voltage (loop) law, and it follows from the fact that energy is neither created nor destroyed.

Red, green and blue are the primary colours of light because mixing them in different proportions produces all other colours.