A chemical reaction occurred because calcium oxide has different properties than calcium and diatomic oxygen. The correct option is A.
<h3>What are chemical reactions?</h3>
A chemical reaction is said to occur when the chemical properties of substances change during the course of the reaction.
From the illustration, the chemical properties of calcium oxide are unique from that of calcium and oxygen. Thus, calcium oxide has become a new substance entirely.
Once a reaction leads to the formation of new substances, such a reaction is a chemical reaction.
More on chemical reactions can be found here: brainly.com/question/22817140
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A) Molar mass gold ( Au) = 196.96 g/mol
1 mole Au ----------- 196.96 g
? moles Au ---------- 35.12 g
35.12 x 1 / 196.96
= 0.178 moles of Au
_____________________________
b) 196.96 g --------------- 6.02x10²³ atoms
35.12 g ---------------- ( atoms ? )
35.12 x ( 6.02x10²³) / 196.96
2.114x10²⁵ / 196.96
= 1.07x10²³ atoms
_____________________________________________
Answer:
I think you can make 26, hope this helped.
Explanation:
When using filter paper chromatography to separate ink, one will observe that more colours are mixed into darker inks. The darker an ink is, the more the colours that will be separated out during chromatography process. Thus, the observation that the darker the ink, the more colours are mixed into it will lead one to believe that ink is a mixture.
Answer:
6 half-lives are required for the concentration of reactant to decrease to 1.56% of its original value.
Explanation:
Using integrated rate law for first order kinetics as:
![[A_t]=[A_0]e^{-kt}](https://tex.z-dn.net/?f=%5BA_t%5D%3D%5BA_0%5De%5E%7B-kt%7D)
Where,
![[A_t]](https://tex.z-dn.net/?f=%5BA_t%5D)
is the concentration at time t
![[A_0]](https://tex.z-dn.net/?f=%5BA_0%5D)
is the initial concentration
Given:
Concentration is decreased to 1.56 % which means that 0.0156 of is decomposed. So,
![\frac {[A_t]}{[A_0]}](https://tex.z-dn.net/?f=%5Cfrac%20%7B%5BA_t%5D%7D%7B%5BA_0%5D%7D)
= 0.0156
Thus,
![\frac {[A_t]}{[A_0]}=e^{-k\times t}](https://tex.z-dn.net/?f=%5Cfrac%20%7B%5BA_t%5D%7D%7B%5BA_0%5D%7D%3De%5E%7B-k%5Ctimes%20t%7D)
kt = 4.1604
The expression for the half life is:-
Half life = 15.0 hours
Where, k is rate constant
So,
<u>6 half-lives are required for the concentration of reactant to decrease to 1.56% of its original value.</u>
