Explanation:
The periodic table is a table that arranges elements based on their atomic numbers into groups and periods.
The groups are the vertical arrangement of elements. All elements in a group share similar chemical properties because they have the same number of elements in their valence shell. The periodic table groups are:
Group Other names
1A or 1 Alkali metals
IIA or 2 Alkaline earth metals
IIIA or 3 Boron family
VIA or 6 Chalcogens
VIIA or 17 Halogens
O-18 Inert elements
IIIB-IIB Transition elements
There are 18 vertical columns divided into 8 tall groups or main groups which are 1A to O. The short groups or subgroups are from numerals 1B to VIII.
The periodic table can be divided into four blocks based on the type of sublevels their valence electrons occupy.
- Group IA and IIA constitute the s-block
- Group IIIA to O constitute the p-block
- The transition elements makes up the d-block
- The lanthanides and actinides makes up the f-block
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Answer:B
Explanation:According to the law of superposition, sedimentary and volcanic rock layers are deposited on top of each other. They harden over time to become a solidified (competent) rock column, that may be intruded by igneous rocks and disrupted by tectonic events.
Answer: Root nodules are associations between bacteria and plant roots responsible for nitrogen fixation.
Explanation:
- As nitrogen present in atmosphere cannot be used by plants directly.
- Nitrogen present in atmosphere is converted into nitrogen compounds by bacteria which is present in root nodules of a plant.
- These compounds of nitrogen are then used by plants for various functions.
Answer:
the correct answer is option A copper and silver
Divide the difference by the accepted value and <span> Multiply times 100 to make the value a percent. Use significant figures in all your calculations. When you subtract (Step #1) round your answer to the correct number of significant figures.</span>
