Answer:
c.boron-11
Explanation:
The atomic mass of boron is 10.81 u.
And 10.81 u is a lot closer to 11u than it is to 10u, so there must be more of boron-11.
To convince you fully, we can also do a simple calculation to find the exact proportion of boron-11 using the following formula:
(10u)(x)+(11u)(1−x)100%=10.81u
Where u is the unit for atomic mass and x is the proportion of boron-10 out of the total boron abundance which is 100%.
Solving for x we get:
11u−ux=10.81u
0.19u=ux
x=0.19
1−x=0.81
And thus the abundance of boron-11 is roughly 81%.
Answer: pure substances.
Explanation:
The given substances are:
All what surrounds us, which has mass and occupies spaces, is matter. There are two kind of matter: pure substances and mixtures.
Pure substances have a uniform and constant composition. On the other hand, mixtures are combinations of two or more pure substances in any arbitratry ratio.
Pure substances may be elements or compounds. The elements are the substances conmposed by one only kind of atom. In the list of substances given, Li and O₂ are elements: all the atoms in Li are lithium, and all the atoms in O₂ are oxygen atoms.
Compounds are the chemical combination of two or more different kind of atoms. In the given list H₂O₂ and NaCl are compounds. As you see, H₂O₂ contains atoms of hydrogen and oxygen, chemically bonded, in a fixed ratio (2 atoms of hydrogen by 2 atoms of oxygen). And NaCl has atoms of Na (sodium) and Cl (chlorine), chemicaly bonded, in a fixed ratio (1:1).
There are only 118 known elements and you can find them in any modern periodic table. Therer are virtually infinitely many compounds since many different combinations of the elements can be attained.
Elements and compounds have in common that they are classified as pure substances.
Answer:
The product of aerobic respiration is Carbon dioxide.
Explanation:
- The process of breaking down glucose to produce energy and waste products is called respiration. Livings beings need respiration process to generate energy so that they can survive.
- The types of respiration are : Anaerobic and aerobic respiration.
- Aerobic respiration takes place in presence of oxygen and produces large amount of energy.
- The final product of aerobic respiration are carbon dioxide, water and 38 ATP of energy.
Answer:
4.1 moles of FeCl₃
Explanation:
The reaction expression is given as shown below:
2Fe + 3Cl₂ → 2FeCl₃
Number of moles of Cl₂ = 6.1moles
So;
We know that from the balanced reaction expression:
3 moles of Cl₂ will produce 2 moles of FeCl₃
Therefore 6.1moles of Cl₂ will produce 
= 4.1 moles of FeCl₃
The number of moles is 4.1 moles of FeCl₃
Answer:
The final pressure of the gas is 0.915atm
Explanation:
We have to apply the Charles Gay Lussac Law, where the pressure changes directly proportional to absolute T°
- No change in volume
- The same moles in both situations
P1 / T1 = P2 / T2
0.991 atm / 342K = P2 / 316k
(0.991 atm / 342K) . 316K = P2
0.915 atm = P2
