Answer:
Volume of the sulfuric acid (25cm³), same mass of each metal (1g)
Explanation:
In an experiment, the CONTROL VARIABLE also known as constant is the variable that is kept unchanged for all groups in an experiment. This is done in order not to influence the outcome of the experiment.
In this case, students are trying to investigate the reactivity of four different metals. They added 1 g of each metal to 25cm³ of sulfuric acid and recorded the temperature change. Based on the explanation of control variable above, the VOLUME OF SULFURIC ACID (25cm³) and the MASS OF EACH METAL (1g) are the CONTROL VARIABLES because they are the same or unchanged in this experiment.
Answer:
The ice will not melt
Explanation:
Given:
Mass of chunk = 0.25 g
moles of sodium = mass / molar mass = 0.25 / 23 = 0.010 g
ΔH = -368 KJ
Hence, 2 moles of Na produced 368 KJ
So 1 mole will produce 368 / 2 KJ and 0.01 mole will produce
= (368 / 2) * 0.01 = 2.0056 KJ
Also, moles of ice = mass / molar mass of water = 50 / 18 = 2.8 g
Energy required to melt the ice = enthalpy of fusion of ice * number of moles of ice
= 6.01 * 2.8 = 16.722 KJ
But we have 2.0056 KJ, so the ice will not melt.
Answer:
Variability of data around the mean is best expressed through the standard deviation.
Explanation:
We have some statistical metrics, and we need to find the best measure of the variability of data around the mean.
First variable is mode. Mode of a set of data values is the value that appears most often. It means the most frequent data.
Second variable is Median. The median is a simple measure of central tendency. It is located around 50% of data range.
Third variable is standard deviation. The standard deviation is found by taking the square root of the average of the squared deviations of the values subtracted from their average value. It means, it will show the dispersion of data around the average value.
According to the definition presents for the three variables, Standard deviation is the most appropriate measure of variability of data around the mean.
Answer:
I think it is iron conducts electricity and heat