Answer:
The energy of the reactants.
Answer : The measurements are both precise and accurate.
Explanation :
Accuracy : It is defined as the closeness of a measured value to a standard or known value.
For Example: If the mass of a substance is 50 kg and one person weighed 48 kg and another person weighed 55 kg. Then, the weight measured by first person is more accurate.
Precision : It is defined as the closeness of two or more measurements to each other.
For Example: If you weigh a given substance five times and you get 1.8 kg each time. Then the measurement is said to be precise.
Level of precision is determined by the maximum number of decimal places.
When the level of precision is very very less, the measurement can be considered as most precise and most accurate.
As we are given the standard value of the sample is 20.000 and the values measured by the balance are, 19.995, 20.005, 20.001.
Since these three values are in the range of +/- 0.005 from one another. So, we can say that the measurements are both precise and accurate.
Hence, the measurements are both precise and accurate.
Answer:
B
Explanation:
We are talking about the periodic table in which elements where put under different rows and columns according to their atomic number (number of protons) in ascendant order.
In rows or periods we can find trends in some properties like atomic radius, electronegativity, etc...). So they are not similar in size. Option A is a false statement.
Also, they were organized in groups or columns according to their similar electronic configuration and chemical properties (like noble gases, halogens, etc...) This means option B is the correct statement.
Which of the following equations can be used to determine the change in enthalpy of a system
ΔHreaction=ΔHproducts−ΔHreactants
