Answer:
When Epsom salt (magnesium sulfate) dissolves, it separates into its ions: a magnesium ion (Mg2+) and a sulfate ion (SO4 2-), which results in hard water. When hard water and soap are mixed, the magnesium ion reacts with soap molecules and forms a solid material called a precipitate, which does not dissolve.
Explanation:
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1. Meteorologist predict the weather by using tools. They use these tools to measure atmospheric conditions that occurred in the past and present, and they apply this information to create educated guesses about the future weather. The best we can do is observe past and present atmospheric patterns and data, and apply this information to what we think will happen in the future. Meteorologists use the scientific method on a daily – and even hourly – basis!
2. They use thermometers, barometers, sling psychrometers and rain gauges. They also use anemometers, hygrometers, weather maps, weather balloons and weather satellites.
The mass of NaCl formed is 8.307 grams
<u><em> calculation</em></u>
step 1: write the equation for reaction
Na₂CO₃ + 2HCl → 2 NaCl +CO₂ +H₂O
Step 2: find the moles of Na₂CO₃
moles = mass/molar mass
The molar mass of Na₂CO₃ is = (23 x2) + 12 + ( 16 x3) = 106 g/mol
moles = 7.5 g/106 g/mol =0.071 moles
Step 3: use the mole ratio to determine the mole of NaCl
Na₂CO₃:NaCl is 1:2 therefore the moles of NaCl =0.07 x2 =0.142 moles
Step 4: calculate mass of NaCl
mass= moles x molar mass
the molar mass of NaCl= 23 +35.5 =58.5 g/mol
mass = 0.142 moles x 58.5 g/mol =8.307 grams
The copper wire was sanded before burning in order to make sure that copper metal was exposed on the surface of the wire.
Answer: B
Explanation
The copper wire when placed in atmosphere without coating leads to oxidation of copper metal with respect to the impurities present in the atmosphere.
As copper is electropositive in nature, so electronegative ions present in the universe will try to react with copper and the copper will react easily with other elements.
So generally copper wire is coated with color or polymer coating.
In this case, the copper wire without any coating is sanded, so that the eddy sheets or polishing materials on friction with copper wire will remove the impurities by the electrostatic law of conservation of charges and charge transfer.
As the impurities are removed when copper wire is sanded, the copper atoms will be exposed on the surface of the wire leading to burning of copper in the copper wire.
A. 1
B. 4
C. 5
D. 3
E. 2
The correct answer is E. 2
