Your Question: There are two kinds of elements that didn't appear on the periodic table until after 1892. What kinds are they and why do you think it took so long to discover them?
The Answer: Moseley’s analysis enabled chemists to refine the table further and reveal more gaps, which suggested that there were more new elements waiting to be discovered, with atomic numbers 43, 61, 72 and 75. Scientists subsequently found these elements—now known as technetium, promethium, hafnium and rhenium, respectively.
Explanation: Physicist Henry Moseley discovered the atomic number of each element using x-rays, which led to more accurate organization of the periodic table. We will cover his life and discovery of the relationship between atomic number and x-ray frequency, known as Moseley's Law.
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The correct type of heat transfer for A, B, and C are conduction, convection and radiation respectively.
<h3>What is heat transfer?</h3>
Heat transfer is a process in which amount of heat will be transferred from one object to any other object by various means.
- In type A, heat is transferred through conduction process as in this transfer takes place due to direct contact of particles.
- In type B, heat is transferred through the convection process as in that process transfer of heat takes place through the medium.
- In type C, heat transfer done by the radiation as in that transfer through empty space.
Hence at A, B and C heat transfer done through conduction, convection and radiation respectively.
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Answer:
To keep the evinermental machinces working
Explanation:
Answer:- 14.0 moles of hydrogen present in 2.00 moles of
.
Solution:- We have been given with 2.00 moles of
and asked to calculate the grams of hydrogen present in it. It's a two step conversion problem. In first step we convert the moles of the compound to moles of hydrogen as one mol of the compound contains 7 moles of hydrogen. In next step the moles are converted to grams on multiplying the moles by atomic mass of H. The calculations are shown as:

= 14.0 g H
So, there are 14.0 g of hydrogen in 2.00 moles of
.
I would say "Greek myths"