Answer:
NaCl= ionic bond.
H2O=covalent bond.
Explanation:
NaCl:
Happens between metal and non-metal. since metal needs to lose an electron to get a full outer shell of electrons, sodium (Na) loses one electron and has a full outer shell of electrons.
chlorine is a gas so it needs to gain electrons to have a full outer shell. since it is in group 7, it needs to gain 1 electron for a full outer shell of electrons.
the lost electron from sodium is given to chlorine. this creates ions (a charged particle) so it is Na+Cl-. this creates a strong electrostatic attraction between the elements and causes them to join together in a lattice form.
H2O:
Covalent bonds happens between 2 gases. they share an electron or 2, and the bonds are very strong.
since oxygen needs 2 molecules to form a full outer shell. hydrogen have 1 atom in outer shell so they share the electron with the oxygen atom.
I can't fully explain why this is for H2O, but I hope you understand it.
In a perfect world without air resistance, the top of the swing would have the most potential energy, but the least amount of kinetic energy. As the pendulum falls down, it gains more kinetic energy as it travels faster due to gravitational acceleration but loses more potential energy as it loses height. The total amount of energy in the system (the sum of kinetic and potential energy) stays the same.
Answer:
The law of conservation of mass applies to both cases
When 50 g of sugar undergoes a physical change, say for example melting, the amount of sugar in the solution or melted form will also be 50 grams. This shows that the mass before and after the change was the same, in accordance to the law of conservation of mass. The mass stays the same.
When the magnesium strip is burned, this is a chemical reaction. The problem is that we only measure the mass of one of the substances involved in the reaction which is the magnesium strip, which makes it seem like the mass has increased. Actually, while burning, the magnesium combines with oxygen in the air. This oxygen was present before the reaction, we just did not measure it. And after the reaction it is present in the form of product. But the mass is still conserved.
Hope this helps!!:)
