It's a physical change because the composition of the salt hasn't change. Only the change in substance/form has occured. To tell if something has undergone physical change is:
• Melting
• Boiling
• Freezing
• Condensing
• Breaking
• Bending
• Dissolving
• Molecules can change motion and proximity
To tell if something changed chemically:
• Molecules rearrange with other molecules to make new substance
• Can be production of flames
• Color change
• Bubbling/fizzing
• Temp. change
• change in composition
Answer:
Option 4. 14.8 g
Explanation:
3NO2 + H2O → 2HNO3 + NO
First let us calculate the molar mass of NO2 and NO. This is illustrated below;
Molar Mass of NO2 = 14 + (2x16) = 14 + 32 = 46g/mol
Mass of NO2 from the question = 3 x 46 = 138g.
Molar Mass of NO = 14 +16 = 30g/mol
From the equation,
138g of NO2 reacted to produce 30g of NO
Therefore, 68.2g of NO2 will react to produce = (68.2 x 30)/138 = 14.8g of NO.
Explanation:
The given data is as follows.
Mass = 27.9 g/mol
As we know that according to Avogadro's number there are 
atom present in 1 mole. Therefore, weight of 1 atom will be as follows.
1 atoms weight = 
In a diamond cubic cell, the number of atoms are 8. So, n = 8 for diamond cubic cell.
Therefore, total weight of atoms in a unit cell will be as follows.
= 
= 
Now, we will calculate the volume of a lattice with lattice constant 'a' (cubic diamond) as follows.
= 
= 
= 
Formula to calculate density of diamond cell is as follows.
Density = 
= 
= 2918.1 
or, = 0.0029 g/cc (as 1 
)
Thus, we can conclude that density of given semiconductor in grams/cc is 0.0029 g/cc.
Answer:
Water, in either liquid or solid form, is often a key agent of mechanical weathering. For instance, liquid water can seep into cracks and crevices in rock. If temperatures drop low enough, the water will freeze. ... This specific process (the freeze-thaw cycle) is called frost weathering or cryofracturing.
D) otherwise we wouldn't be able to have water, oxygen gas, and all other compounds that have oxygen. We need at least 1 free slot to make a molecule
