Answer:
In order to answer the question, we convert the measurements given to a common base unit. For this case, we use seconds.
A) 0.02 seconds
B) 0.02 teraseconds x (10^12 s / 1 terasecond) = 2x10^10 seconds
C) 2,500 milliseconds x (1 s / 1000 ms) = 2.5 seconds
D) 25,000 nanoseconds x (1 x 10^-9 s / 1 nanosecond) = 2.5 x 10^-5 seconds
So ,The correct answer is option " D "
Answer:
1. Density can be used to identify a substance
2. Density can be used to ascertain whether a substance will float in water.
Explanation:
The calculation of the density of a substance can be used to identify the substance. If the density of a substance is calculated accurately, and compared with a table of standard densities, then we can identify that substance.
Also, density determines whether an object will float or sink in water. If an object is less dense than water then it will float in water. If it is denser than water, then it will sink in water.
HCl:
<span>
m=48,2g
M=36,5g/mol
n = m/M = 48,2g / 36,5g/mol = 1,32mol
1mol : 4mol
MnO</span>₂ + 4HCl ⇒ MnCl₂ + Cl₂ + 2H₂O
0,86mol : 1,32mol
limiting reagent
0,33 will react
HCl is limiting reagent.
Answer:
2KClO3 -------> 2KCl + 3O2
Explanation:
First, in balancing a chemical reaction such as the one given in the question, you should understand that for an equation to be balanced, the number of atoms and ions on both sides of the equation that is the right and left side must be equal. This follows the law of conservation of mass which tells us that matter can neither be created nor destroyed but can be changed into another form.
Next is to begin balancing the equation by identifying and writing down the substances given:
KCl03 ---------> KCl + O2
Next is to count he number of the individual atoms on each side and find out if they are the same on both sides and if not you must follow the next step.
Add a corresponding number and use it to multiply the atoms involved
KClO3 ---------> KCl + O2
Oxygen is 3 on the left side and two on the other side, so we multiply the left hand side by 2 and the right hand side by 3
2KClO3 -----> KCl + 3O2
The potassium and Chlorine are no longer balanced, so you multiply the right had=nd side of KCl by 2.
2KClO3 -----> 2KCl + 3O2
The reactionis herefore balanced as both sides have equal number of atoms and ions.
Half-life of a radioactive substance is the time required to reduce the amount of substance to half of its initial amount.
In present case, half-life is material is given as 1000 years and initial amount of material is given as 400 kg
Answer 1) Since, half-life of radio-active substance is 1000 years, therefore after 1st half life, amount of the material will be left to half the initial amount. Hence, amount of substance left after 1000 years = 400/2 = 200 kg.
Answer 2) For 2000 years, radioactive material has crossed 2 times the half life. Therefore , amount of the material will be left to 1/4 the initial amount. Hence, amount of substance left after 2000 years = 400/4 = 100 kg.
Answer 3) For 4000 years, radioactive material has crossed 4 times the half life. Therefore , amount of the material will be left to 1/16 the initial amount. Hence, amount of substance left after 4000 years = 400/16 = 25 kg.
