Answer:
+ 3
Ex planation:
Al3+ indicates an ion of aluminum having a charge of + 3. I.e., since an aluminum atom normally has 13 protons and 13 electrons, this ion has 10 electrons (-10 charge) and 13 protons (+ 13 charge) giving it a charge of + 3 (-10 + 13 = +3).
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Answer:
It will sink.
Explanation:
Density of water=1gm/cc (In CGS)
Volume of cube=l^3 =3^3= 27cc
Mass of cube =54gm
Density of cube=M/V =54/27 =2gm/cc
Here, density of cube is greater than that of water. So, the cube sinks.
The best and most correct answer among the choices provided by your question is the fourth choice or letter D. Natural run-off from mountain ranges <span>is thought to be most responsible for the salinity of the oceans.
</span>After years and years of river inflow and evaporation, the salt<span> content of the lake water built up to the present levels. The same process made the seas </span>salty<span>. Rivers carry dissolved salts to the </span>ocean<span>. Water evaporates from the </span>oceans<span> to fall again as rain and to feed the rivers, but the salts remain in the </span>ocean<span>.</span>
Explanation:
a) Bohr model is perfect for atoms that have single electron and fortunately both Be3+ ion and H atom have one electron so, Bohr model can easily and accurately applied to predict the spectrum of Be3+ and H atom.
b) The energy of an atom in Bohr model is given by

the values of z for H atom and Be3+ ion are 1 and 4 respectively. Hence, energy of atoms would be different for both atoms. Hence, line spectra to be identical is not possible.
Answer:
Refer to the period table. Use the atomic mass for calculation. Multiply the atomic mass with the number of atoms. For example, Al2(SO4)3. (27 × 2) + (32 x 3) + (16 x 12) = molecular mass