Answer:
Metric ruler
Explanation:
You need to measure length, which is exactly what a ruler measures. The other option measure other things, like liquids or temperature.
Answer:
irreversible chemical change
Explanation:
A chemical change always results in a new substance and as it is not possible to reverse it, it is an irreversible chemical change.
I hope you understood :)
Answer:
Option b. Lowering the pH to kill pathogenic bacteria is correct answer.
Explanation:
bacterial motors are sensitive to pH. By decreasing the pH bacterial motors stops working. This was identified in a new research. But, with the weak acids and a lower internal pH they slow and ultimately stop moving (became dead).
Reference: Powell, K. Acid stops bacteria swimming. Nature (2003).
Answer:
Covalent bonds form when two atoms share valence electrons,
while Van der Waals forces cause an attraction between nonpolar
molecules
Explanation:
A covalent bond is said to be formed when two atoms of the same or different elements share electrons. In an ordinary covalent bond, each bonding atom contributes one valence electron while in a dative covalent bond only one of the bonding atoms provides the shared pair of electrons.
Van Der Waals forces is the major intermolecular interaction between non polar compounds. Van Der Waals forces " are caused by correlations in the fluctuating polarizations of nearby particles"(Wikipedia).
