Answer: 
Explanation:
Significant figures : The figures in a number which express the value or the magnitude of a quantity to a specific degree of accuracy is known as significant digits.
Rules for significant figures:
Digits from 1 to 9 are always significant and have infinite number of significant figures.
All non-zero numbers are always significant.
All zero’s between integers are always significant.
All zero’s after the decimal point are always significant.
All zero’s preceding the first integers are never significant.
Thus has three significant figures
Answer:
The answer is: A
Explanation:
The wave-like contractions are to be considered a physical change as they do not take part in the breaking-down of the food. The peptidase is a chemical change because it is used to chemically break down the food to retrieve nutrients and such.
Answer:
C₂H₂O₃
Explanation:
The empirical formula of a compound is derived bu finding the whole ratios of the constituent elements.
In succinic acid, the ratios of carbon to hydrogen to oxygen is calculated as follows:
<u>% mass</u>
Carbon- 40.60
Hydrogen - 5.18
Oxygen - 54.22
<u>RAM</u>
Carbon -12
Oxygen - 15.994
Hydrogen -1.008
<u>No of moles elements in the compound</u>
Carbon = 40.60/12=3.3833
Oxygen = 54.22/15.994= 3.39
Hydrogen= 5.18/1.008 = 5.1389
Mole ratios of the individual elements we divide by the smallest value of the number of moles.
Carbon: Hydrogen : Oxygen
3.3833/3.3833:3.39/3.3833:5.1389/3.3833
=1:1:1.5
We can multiply the value by 2 to get the whole number ratio.
=2:2:3
The empirical formula will be:
C₂H₂O₃
<h3>The enthalpy of combustion per mole of anthracene : 7064 kj/mol(- sign=exothermic)</h3><h3>Further explanation </h3>
The law of conservation of energy can be applied to heat changes, i.e. the heat received/absorbed is the same as the heat released
Q in = Q out
Heat can be calculated using the formula:
Q = mc∆T
Heat released by anthracene= Heat absorbed by water
Heat absorbed by water =
mol of anthracene (MW=178,23 g/mol)
The enthalpy of combustion per mole of anthracene :
Elements in same group / family tend to have similar properties ( but not exactly the same). Since, iron and silver are in two different group / families, they have different properties.
Also, Silver and iron have different properties because they have different atomic structure. Having different atomic structure means bonding differently with other elements. So, they have different properties.
