Answer is: -601,2 kJ/mol
Chemical reaction: Mg(OH)₂ → MgO + H₂O.
ΔHrxn = 37,5 kJ/mol.
ΔHf(Mg(OH)₂) = <span>−924,5 kJ/mol.
</span>ΔHf(H₂O) = <span>−285,8 kJ/mol.
</span>ΔHrxn -enthalpy of reaction.
ΔHf - enthalpy of formation.
<span>ΔHrxn=∑productsΔHf−∑reactantsΔHf.
</span>ΔHf(MgO) = -924,5 kJ/mol - (-285,8 kJ/mol) + 37,5 kj/mol.
ΔHf(MgO) = -601,2 kJ/mol.
im not understanding the question, but if its a solid then the reactants are precipitate
The mass of piece of sterling silver jewelry is 33.24 g. It contains 92.5% silver Ag by mass. Since, sterling silver is an alloy of Ag-Cu thus, percentage of Cu will be:
% Cu=100-92.5=7.5%
Thus, mass of copper will be:
Molar mass of Cu is 63.546 g/mol, thus, number of moles of Cu can be calculated as follows:
Here, m is mass and M is molar mass.
Putting the values,
Now, in 1 mole of Cu there are 
thus, in 0.03923 mol, number of Cu atoms will be:
Thus, number of atoms of Cu will be
.
Answer:
Option c and d
Explanation:
John Dalton. In 1808, John Dalton proposed a theory known as Dalton’s Atomic Theory. The theory was published in a paper titled “A New Chemical Philosophy”. This theory was new to that era
The 5 postulates of Daltons' atomic theory are:
1. All the matters are made of atoms.
2. Atoms of different elements combine to form compounds
3. Compounds contain atoms in small whole-number ratios
4. Atoms can neither be created nor destroyed
. (This was later proven wrong )
5. All atoms of an element are identical and have the same properties (This was later proven wrong as atoms of same element may be different in case of elements having isotopes )
Therefore, options c and d are the answer.
<span>ATP,O2 and NADPH are the </span>products<span>. H2O,NADP,ADP and Pi are the reactants. acts as an electron carrier between the cytochrome b6f and </span>photosystem 1 (PS1) complexes in the photosynthetic electron-transfer chain.
Photosystem II<span> (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants, algae, and cyanobacteria.</span>
