Write structures for the following compounds.(a) 3-ethyl-4-methylhexane (b) 3-ethyl-5-isobutyl-3-methylnonane(c ) 4-tert-butyl-2-methylheptane (d) 5-isopropyl-3,3,4-trimethyloctane

Here's what I get  

Explanation:

(a) 3-Ethyl-4-methylhexane

The main chain is eight carbons long, with an ethyl group at C-3 and a methyl group at C-4

(b) 3-Ethyl-5-isobutyl-3-methylnonane

The main chain is nine carbons long, with an ethyl group and a methyl group on C-3 and an isobutyl group on C-5.

Note that the name isobutyl is acceptable in general use, but the preferred IUPAC name (PIN) for the group is now (since 2013) "2-methylpropan-2-yl".

The PIN for your compound is 3-ethyl-3-methyl-5-(2-methyl propan-2-yl)nonane.

(c) 4-tert-butyl-2-methylheptane

The main chain is seven carbons long, with a tert-butyl group at C-4 and a methyl group at C-2.

For some reason, the IUPAC has retained the name tert-butyl for the group, so the name you give is the PIN.

The prefix "tert" is written in italics.

(d) 5-isopropyl-3,3,4-trimethyloctane

The main chain is eight carbon atoms long, with two methyl groups on C-3 and one on C-4, and an isopropyl group on C-5.

The PIN for an isopropyl group is now "propan-2-yl", so the IUPAC name for your compound is 3,3,4-trimethyl-5-(propan-2-yl)octane.

answer; /// the amount of material dissolved in a measure of liquid(concentration) the above statement is (true); /// good luck

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.