QA › Chemistry

Chemistry answers to 20 questions

Hello! As a rule, chromosomes become visible during prophase, so, the correct version is B. Prophase is the first and the longest phase of mitosis, and during this stage nuclear membrane breaks down and chromosomes become visible.
5 Views
Correct answer is B - dipole-dipole. Dipole-dipole interaction is much stronger than London dispersion forces, but weaker than covalent or ionic bonds. It equals 5-10 kJ per mole.
5 Views
In this case, you should use the formula for finding the maximum number of stereoisomers for a compound: N max = 2m, where n = the number of chiral centers So, the calculations for your example will look as follows:…
7 Views
As a rule, we use roman numerals in the name of a compound when a metal cation forms two ions with different states of oxidation. For instance, Cu can form two different ions - Cu+ and Cu 2+. Combining with…
3 Views
Atomic mass is a mass of a single atom, it can be calculated as a sum of neurons and protons in the atom. In turn, a molar mass is a mass of a substance (in grams) divided by the number…
4 Views
Here's the answer: When an atom emits an alpha particle, it transforms into a different element, therefore, its atomic number will be reduced by two.
5 Views
Water can dissolve the ionic compound because of the diference between its hydration and lattice energy.
5 Views
The given mass of an element can be found using Avogadro's number, which equals 6.02214076 × 1023 mol-1 and gives you one mole of anything. 1. You determine the molar mass of the element. 2. Then, you divide the given…
5 Views
Correct answer is 1. MgO is expected to have the highest lattice energy.
7 Views
Hi there! BrCl3 is definitely a polar molecule, it is evident from its T-shaped molecular geometry.
5 Views
No of protons - 29 No of neutrons - 35 No of electrons - 29 Explanation: Since the atomic number of copper is 29, the number of protons equals 29 as well. Since the atom is neutral, the number of…
7 Views
First, you should write a molecular equation: MgCl2(aq) + 2NaOH(aq) ==> Mg(OH)2(s) + 2NaCl(aq) Then, the net ionic reaction will equal: Mg^2(aq) + 2OH^-(aq) ==> Mg(OH)2(s)
5 Views
Here's the solution: The rate of the reaction is R R = - 1/5 * (d*[Br2])/dt The average rate of consumption of bromine is 1.76 * 10-4 M/s, therefore, - d*[Br]/dt = 1.76 * 10-4 M/s The average rate of…
4 Views
First, let's define the standard enthalpy values (H): 02(g) = 0 kj/mol CO2 (g) = -393.5 kj/mol H20(g) = -241.8 kj/mol According to the instructions, heat per mole produced (H) equals 5094 kj Therefore, -5094 kj is your H total.…
5 Views
First of all, we need to find the average rate if disappearence for A, where the formula is -ΔC/Δt First rate (A) = -ΔC/Δt = - (0.430-0.720)/(196-0) = 1.48 * 10-3 mol/(L*s) Second rate (A) = -Δc/Δt = - (0.140-0.430)/(392-196)…
10 Views
The first step should be writing out a balanced equation. To do that, you should remember that ethanol is a hydrocarbon derivative and burns the same ways as hydrocarbons yielding H20 and CO2 as end products.  With that in mind,…
4 Views
The solubility of Copper Sulphate will decrease. That’s why precipitate CuSO*5H2O  will be formed.
2 Views
Solution: N2(g)+2O2(g)-->2NO2(g)   ?H°1=+66.4kJ 2NO2(g)-->  2NO(g)+O2(g)   ?H°2=+114.2kJ Add the rxns to get an answer: N2(g)+2O2(g)-->2NO2(g) ?H°1=+66.4kJ 2NO2(g)--> 2NO(g)+O2(g) ?H°2=+114.2kJ So the answer is N2(g) +  O2(g)  --> 2NO(g) 66.4kJ + 114.6 kJ = 181kJ.
5 Views
F - false T - true a.It is an organic molecule. - T b.It contains thirteen different chemical elements. - F c.Its chemical formula can be written as C3H7NO2. -  depends on writing - T d.Each of the carbon atoms…
3 Views
Answer: Alkyl halides contain C-Hal bond. The bond is polar, because halogens are more polar that Carbon. There are dipole-dipole interactions between alkyl halides. Water also polar molecule, but there are hydrogen bonds between these molecules. When water and an alkyl…
2 Views