Answer: B. An experiment that directly tests the hypothesis
Explanation:
Yasir didn’t really test his experiment he only ask people for the opinion on which color they like so he forget to actually do the experiment therefore the answer is b.
Explanation:
A.ph 6 B. correct ph goes in a scale up to 14 below 7 is acidic above 7 is basic and in the middle is newtral when they say pH they are asking how acidic is it when they ask for pOH they are asking how basic it is pH is calculated using logs as is pOH so ans
12.65
Answer:
protons and neutrons are found in nucleus
The outermost energy shell of an atom
because they are involved in forming bonds
It would take 147 hours for 320 g of the sample to decay to 2.5 grams from the information provided.
Radioactivity refers to the decay of a nucleus leading to the spontaneous emission of radiation. The half life of a radioactive nucleus refers to the time required for the nucleus to decay to half of its initial amount.
Looking at the table, we can see that the initial mass of radioactive material present is 186 grams, within 21 hours, the radioactive substance decayed to half of its initial mass (93 g). Hence, the half life is 21 hours.
Using the formula;
k = 0.693/t1/2
k = 0.693/21 hours = 0.033 hr-1
Using;
N=Noe^-kt
N = mass of radioactive sample at time t
No = mass of radioactive sample initially present
k = decay constant
t = time taken
Substituting values;
2.5/320= e^- 0.033 t
0.0078 = e^- 0.033 t
ln (0.0078) = 0.033 t
t = ln (0.0078)/-0.033
t = 147 hours
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