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Answer:
Element with the smallest radius is Carbon.
Explanation:
In a periodic table, atomic radius increases down the group due to addition of a new shell and decreases across the period from left to right due to increasing nuclear charge.
Due to addition of more electrons in same shell and increase of positive charge in nucleus increases attractive forces between electrons and nucleus hence decreasing size.
Carbon and Lithium are present in same period and hence Carbon has smaller size; Potassium and Bromine are present in same period and hence out of the two, Bromine has smaller size.
On comparing Carbon and Bromine, atomic radius increases down the group hence, Carbon has the smallest radius among the four given elements.
The maximum amount of hydrogen gas that can be prepared is if all the hydrogen from both compounds is released.
The hydrogen in 4.94 g of SrH2 is calculated from the mass ratios between Sr and H
1) H2 in SrH2
Sr atomic mass = 87.62 g/mol
H2 molar mass = 2.02 g/mol
Mass of 1 mol of SrH2 = 87.62 g / mol + 2.02 g/mol = 89.64 g/mol
Ratio of H2 to SrH2 = 2.02 g H2 / 89.64 g SrH2
Proportion: 2.02 g H2 / 89.64 gSrH2 = x / 4.93 g SrH2
=> x = 4.93 g SrH2 * 2.02 g H2 / 89.64 g SrH2 = 0.111 g H2
2) H2 in H2O
2.02 g H2 / 18.02 g H2O * 4.14 g H2O = 0.464 g H2
3) Total mass of hydrogen = 0.111 g + 0.464 g = 0.575 g
Answer: 0.575 g
Answer;
c.electrons move from the wool to the rod.
Explanation;
-Atoms are generally neutral (have the same number
of protons as electrons). Substances lose electrons to become
positively charged, while other substances gain electrons to become negatively charged.
-When a plastic rod is rubbed with woolen
cloth or wool, a transfer of electrons occurs (from the wool to the rod). The rod gains electrons; thus, it
is negatively charged.
