The atomic number of an element is 8. Its valency is:
A. 6
B. 8
C. 4
D. 2
Answer: Option D
Solution (By JKExamLibrary)
Atomic number 8 is oxygen (2,6). It needs 2 more electrons to complete octet, so it gains 2 or shares 2 electrons. Its valency is 2 (typically). It can form two covalent bonds. In H₂O, oxygen forms two bonds.
Explanation:
The long hydrocarbon chain (tail) of soap is non-polar and hydrophobic, so it dissolves into the oily/greasy dirt particle. The ionic head (hydrophilic) remains in the water. This forms a micelle around the dirt, emulsifying it and allowing it to be washed away. The tail-dirt interaction is via van der Waals forces.
Explanation:
CH₄ + 2O₂ → CO₂ + 2H₂O + heat. Complete combustion of any hydrocarbon with sufficient oxygen always produces carbon dioxide and water. Incomplete combustion due to limited oxygen produces carbon monoxide (CO) and/or soot (carbon particles). Methane is the main component of natural gas and biogas. CO is a poisonous gas. The combustion of alkanes is highly exothermic.
No comments yet. Be the first to start the discussion!