Which of the following combination of elementary substances may react to form a chemical compound made up of molecules? - c(s) and br2(i) -i2(s) and mg(s) -o2(g) and na(s) - all of them react to produce compounds made up of molecules

-

Only C(s) and Br2(l)

Explanation: -

Ionic compounds are formed between metals and nonmetals.

We use the term molecule when covalent compounds are formed but not for ionic compounds. In the case for Na(s) and O2(g), an ionic compound is formed. Similarly between Mg (s) and I2(s) an ionic compound is formed.

Only between C(s) and Br2 (l) a covalent compound  gets formed. These compound is formed of molecules.

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.