Answer: A
Explanation:
This means that the atomic number decreases by 1 but the mass remains constant, meaning the atomic number of the new element is 20. This corresponds to calcium.
Answer:
2 moles of Substance B
Explanation:
Because 1 mole of any substance contains 6.02× 10²³ particles either atoms, molecules, ions or even electron(Avogardo Constant)
Therefore 12.04 × 10²³/ 6.02× 10²³ = 2 mole of Substance B
Answer:
End point
Explanation:
The point at which the indicator changes color is called the endpoint. So the addition of an indicator to the analyte solution helps us to visually spot the equivalence point in an acid-base titration
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The primary reason for this was that Mendeleev
didn't know that atomic numbers actually existed. Atomic numbers
were only discovered a period after Mendeleev's time. The use of X-rays made it
possible to find the atomic number, and those had not been discovered yet. <span>
<span>The periodic table was then arranged in 1913 by Henry Moseley
in an arrangement according to atomic number.</span></span>
Ammonia is colorless gas with a characteristic smell. Its density is 0.589 times than air which makes it lighter than air. Ammonia can be easily liquefied due to the hydrogen bonding between the molecules. The boiling point is at -33.3 degrees Celsius and the freezing point is at -77.7 degrees Celsius.
