Answer:
Explanation:
250 cm^3 of 0.2 moldm-3 H2SO4 can be prepared from 150cm^3 of 1.0 moldm^-3 by dilution.
150cm^3 of the 1.0 moldm^-3 stock solution is measured out using a measuring cylinder and transferred into a 250 cm^3 standard volumetric flask and made up to mark. The resulting solution is now 250cm^3 of 0.2 moldm-3 H2SO4.
Answer:
When scientist find new species that may have to change classification systems in order to accommodate them. DNA sequencing has also let us find out more about evolutionary relationships. The more recent the common ancestor, the more closely related the two species are.
Explanation:
Answer:
a. True
Explanation:
Methyl red is an indicator widely used in quality control of oxides as Zinc oxide in the titration with sulfuric acid.
As is used in titrations of acid-base reactions the indicator change in colour. Is red when the pH < 4.4 (Acidic Solutions) and is yellow when pH > 6.2 (Neutral-Basic solutions).
A change in colour means the structure of the indicator is changing with pH. Thus, the answer is:
<h3>a. True
</h3>
The electron configuration
1
s
2
2
s
2
2
p
6
3
s
2
3
p
2
is the element Silicon.
The key to deciphering this is to look at the last bit of information of the electron configuration
3
p
2
.
The '3' informs us that the element is in the 3rd Energy Level or row of the periodic table. The 'p' tells us that the element is found in the p-block which are all of the Groups to the right of the transition metals, columns 13-18. The superscript '2' tells us that the element is found in the 2nd column of the p-block Group 14.
