Mg + 1/2 O2 → MgO
1 mol = 24 g of Mg
X mol = 12 g of Mg
x = 0.5 moles of Mg
Mg :MgO = 1:1 (coefficient from equations using mole ratio)
So
0.5 moles of MgO
1 mol MgO = (24+16) g = 40 g
0.5 moles of MgO = 0.5 × 40
= 20 g of MgO produced
Answer: Metals form cations.
The alkali metals (the IA elements) lose a single electron to form a cation with a 1+ charge.
The alkaline earth metals (IIA elements) lose two electrons to form a 2+ cation.
Aluminum, a member of the IIIA family, loses three electrons to form a 3+ cation.
Therefore, metals in the s and p block of the periodic table have 1, 2 or 3 electrons in their outermost orbit (or valence shell). Now to gain a stable octet metals lose either 1, 2 or 3 electrons from the valence shell thus forming cation with +1, +2 or +3 charge.
An endothermic chemical reactions products tend to have a higher potential energy than the reactants. Thus making the /\ H positive, not negative.
Scratching causes cracks and crevices on the surface of the flask (though microscopically). These will act as favorable sites for nucleation, which leads to the formation of crystals.
Answer:
option C= hydrolysis and break down
Explanation:
All other three pairs are correct coupling of each others.
Option A= dehydration synthesis and hydrolysis
Dehydration synthesis:
In dehydration synthesis monomers combine through the covalent bonds and form large molecules. The large molecules are called polymers. The water as a byproduct also released when monomers joints together.
Hydrolysis:
In hydrolysis the polymers are break down into monomers by using water molecules. The catalysts are also required in this process.
Option B= Catabolic and Anabolic
Anabolic:
In this process smaller molecules combine to gather to form large complex molecules by using energy.
For example simple glucose molecules join together to form large disaccharides.
Catabolic:
It is the break down of large complex molecules to the smaller molecules.
For example during cellular respiration sugar molecules break down and generate energy.
Option D= Break down and synthesis
The break down and synthesis are also reverse pair of each others. The synthesis involve the formation of molecules form smaller component while the break down involve destruction of molecules into smaller units.
