Answer:A) It was developed from past observations- true
It is subject to experimentation and revision.- false
It explains why mass is conserved- false
It predicts future observations-true
Explanation:
Before a hypothesis is proclaimed to be a law in science, numerous observation must have confirmed its validity and rigorous experimentation under carefully controlled conditions usually precedes the acceptance of a hypothesis as a law. The law of conservation of mass was developed from numerous past observation that proved its validity.
The atomic number=5
The mass number=11
<h3>Further explanation</h3>
In the following element notation,
X = symbol of elemental atom
A = mass number
= number of protons + number of neutrons
Z = atomic number
= number of protons = number of electrons, on neutral elements
So for The atomic notation for a particular atom of Boron :
₅B¹¹
Z=5=atomic number
A=11=mass number
Answer:
you can identify an unknown substance by measuring its density and comparing your results to a list of known densities. Density=mass/volume. Assume that you have to identify an unknown metal. You can determine the mass of the metal on a scale.
<h3><u>Answer;</u></h3>
C. 3Mg + Al2O3 → 3MgO + 2Al
<h3><u>Explanation;</u></h3>
- <u><em>Single replacement reaction is a type of reaction which one reactant reacts with another and makes a product by replacing one element by another. </em></u>
- Mg (Magnesium) reacts with Al₂O₃ (Aluminium oxide) and produces MgO (Magnesium oxide) and Al (Aluminium) as products. Here Al is replaced by Mg. Reaction is
Mg + Al₂O₃ → MgO + Al
- To balance the reaction equation, both left and right hand sides should have same number of atoms in each element.
The balanced equation will be;
3Mg + Al2O3 → 3MgO + 2Al
