Answer:
Explanation:
21. Atoms are not created or destroyed means that atoms that you begin with are the atoms that you will end with. The catch is that the atoms will rearrange to give you new compounds, but the atoms that you initially had are the atoms you will still have after reaction. For eg, if you started with eggs and made omelet. Omelet is a "new" compound, but the atoms that were in the eggs have rearranged to become the omelet so can you see that atoms were not created or destroyed to make the omelet.
22. Yes because amount of products you make depends on how much reactants you have. For eg, I need two graham cracker(GC), one marshmallow(M), and one chocolate (C) to make a s'more. If I get more of each item then I can make more s'mores and consequently having minimum amounts results in less s'mores that I make.
23. Not possible, due to law of conservation of matter and energy. Atoms cannot be created nor be destroyed, they are simply rearranged. For eg, Taking A + B cannot give you a new compound with a chemical formula D or XZ. A + B can however give you AB which is rearrangement of the starting atoms.
24. Chemical equation is balanced when atoms on reactant side and atoms of product side are in equal counts. I have attached a graphic below for more help.
Answer : The final concentration of 
is, 2.9 M
Explanation :
Expression for rate law for first order kinetics is given by:
where,
k = rate constant = 
t = time passed by the sample = 3.5 min
a = initial concentration of the reactant = 3.0 M
a - x = concentration left after decay process = ?
Now put all the given values in above equation, we get
Thus, the final concentration of is, 2.9 M
Answer:
239.45 K
Explanation:
Ideal gas law formula is P1V1T2=P2V2T1
Rearrange that to get...
T2=T1P2V2/P1V1
Fill in the values and solve.
Answer:
.
Explanation:
Based on the electron configuration of this ion, count the number of electrons in this ion in total:
.
Each electron has a charge of 
.
Atoms are neutral and have 
charge. However, when an atom gains one extra electron, it becomes an ion with a charge of . Likewise, when that ion gains another electron, the charge on this ion would become 
.
The ion in this question has a charge of . In other words, this ion is formed after its corresponding atom gains two extra electrons. This ion has 
electrons in total. Therefore, the atom would have initially contained 
electrons. The atomic number of this atom would be 
.
Refer to a modern copy of the periodic table. The element with an atomic number of is sulphur with atomic symbol 
. To denote the ion, place the charge written backwards ("
" for a charge of ) as the superscript of the atomic symbol:
.
Answer : The correct option is, Malleable, shiny, and able to conduct heat or electricity.
Explanation:
Metals : Metals are the elements which can easily loose electrons and forms cations.
Properties of metals :
- They are lustrous (shine).
- They are malleable and ductile (flexible).
- They conduct heat and electricity.
- The metallic oxides are basic in nature.
- They form cations in an aqueous solution.
Non-metals : Non-metals are the elements which can easily gain electrons and form an anion.
Properties of non-metals :
- They are non-lustrous.
- They are brittle and hard in nature.
- They do not conduct heat and electricity.
- The non-metallic oxides are acidic in nature.
- They form anions in an aqueous solution.
Hence, from the given options the correct option for metal is, Malleable, shiny, and able to conduct heat or electricity.
