There are four compounds with the
formulac4h9br. list them in order
ofdecreasing activity in an sn2 reaction.

The four compounds with formula C4H9Br are

1. 1- Bromobutane

2. 2-Bromobutane

3. 1-bromo-2-methyl propane

4. 2-Bromo-2-methyl propane

Reactivity towards SN2 in decreasing order is :

1- Bromobutane >  1-bromo-2-methyl propane > 2-Bromobutane >

2-Bromo-2-methyl propane

Explanation:

SN2 reaction : This is also known as second order nucleophilic Substitution Reaction because :

The rate determining step depends both on the concentration of the substrate as well as nucleophile.This reaction involve formation of 5- bond transition state (not the intermediate)The bond making and breaking occur simultaneouslyThe reactivitey order for SN2 is more for less hindered substrate i.e :

Primary > Secondary > tertiary

Among the isomers of C4H9Br

The primary halides are : 1- Bromobutane and 1-bromo-2-methyl propane

(Br is attached to primary carbon)

but 1- Bromobutane is less hindered than 1-bromo-2-methyl propane

So,1- Bromobutane >  1-bromo-2-methyl propane

Secondary :2-BromobutaneTertiary : 2-Bromo-2-methyl propane

Hence order is :

1- Bromobutane >  1-bromo-2-methyl propane > 2-Bromobutane >

2-Bromo-2-methyl propane

Answerd. may include all of these are many definitions of bases: the  brønsted-lowry definition of acids and bases says that bases are proton acceptors.the arrhenius definition of acids and bases says that bases increase [oh⁻] in solution (thereby producing oh⁻ ions)the lewis definition of acids and bases says that bases donate electron pairs.therefore, the sensible answer is that a base may include all of the described characteristics.

Answer two atoms of oxygen;