Mass of MnO2 = 25 g
The reaction would be 3MnO2 + 4Al --> 3Mn(s) + 2Al2O3
Molar mass of Al = 26.982 g/mol
Molar mass of MnO2 = 54.938 + 2(15.999) = 86.936 g/mol
Calculating the moles = 25 / 86.936 = 0.2876 mol.
Mole ratio MnO2 and Al considering the equation = 3 mol of MnO : 4 mol of Al
Calculating the moles of Al = 0.2876 mol MnO2 x (4 mol of Al / 3 mol of MnO)
Number of moles of Al = 0.3834
Getting the mass in grams as asked = 0.3834 mol x 26.982 g/mol = 10.34 grams.
The partial pressure<span> of </span>water<span> in the mixture, P</span>water<span>, is the equilibrium </span>vapour pressure<span> of </span>water<span> at the temperature specified. At 298 K, from the data at the beginning of the questions section, P</span>water<span> = 3.17 kPa. Using the Ideal Gas Equation, the number of moles of N</span>2<span> can be calculated.</span>
The thing that governs whether a reaction is exothermic is the energy given out / used up to break / form the bonds in the reaction.
<span>When two substances react, the bonds in those substances first break up, releasing energy, before re-forming in a different way, taking in energy. The nature of the bonds that are broken up and reformed determines whether more energy is given out (exothermic) or taken in (endothermic)</span>

Here's the procedure to Crack an egg ~
Step 1 ~
- Hold the egg in your hand and tap it on a firm surface
Step 2 ~
- Gently pull the shells apart
Step 3 ~
- And release the yolk in the bowl
Answer:
Scheme is Attached.
When 3,5 dimethyl-4- octene is react with ozone two products are obtain.
2-Methyl butanal and 2 pentanon.
The complete reaction is given in attached file.