Chemistry - Study Mode

[#1096] In addition to hydrogen, the other abundant element present on Sun’s surface is
Correct Answer

(A) Helium

Explanation

Solution: The Sun is composed primarily of the chemical elements hydrogen and helium
they account for 74.9% and 23.8% of the mass of the Sun in the photosphere, respectively. All heavier elements, called metals in astronomy, account for less than 2% of the mass. The Sun inherited its chemical composition from the interstellar medium out of which it formed: the hydrogen and helium in the Sun were produced by Big Bang nucleosynthesis.

[#1097] The most abundant element by number in the living system is :
Correct Answer

(B) Hydrogen

Explanation

Solution: In sequential order, Hydrogen, Oxygen, Carbon and Nitrogen are the most abundant elements by number in the living system. Hydrogen constitutes 49.8% of living systems, while Oxygen constitutes 24.9%
Carbon and Nitrogen account for 24.9% and 0.27% respectively. It is not surprising, therefore, that the living cell is between 60% and 90% water.

[#1098] Name two elements that find wide application in transistor industry.
Correct Answer

(A) Silicon and Germanium

Explanation

Solution: A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. Semiconductor material (date first used): the metalloids germanium (1947) and silicon (1954) — in amorphous, polycrystalline and mono-crystalline form
the compounds gallium arsenide (1966) and silicon carbide (1997), the alloy silicon-germanium (1989), the allotrope of carbon graphene (research ongoing since 2004), etc.

[#1099] When there are two electrons in the same orbital, they have:
Correct Answer

(B) Opposite spin

Explanation

Solution: When there are two electrons in the same orbital, they have opposite spins. The Pauli exclusion principle states that there can only be a maximum of two electrons for every one orientation, and the two electrons must be opposite in spin direction
meaning one electron has ms=+21 and the other electron has ms=−21.

[#1100] Which one of the following elements is least likely to be found in commercial fertilisers?
Correct Answer

(D) Silicon

Explanation

Solution: Fertilizers typically provide, in varying proportions: (i) six macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)
and (ii) eight micronutrients: boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn) and nickel (Ni).