The correct answer is option A. Energy cannot be created during an ordinary chemical reaction. There is no such thing as an ordinary chemical reaction. Energy cannot be created or destroyed this is according to the law of conservation of energy. It can only be transformed from one form to another form.
Atomic mass Calcium ( Ca) = 40.078 u.m.a
40.078 g --------------- 6.02x10²³ atoms
187 g ------------------- ??
187 x ( 6.02x10²³) / 40.078 =
1.125x10²⁶ / 40.078 = 2.808x10²⁴ atoms
hope this helps!
Answer:
Density, 
Explanation:
The attached figure shows a 38.6 kg marble slab. The dimensions of the marble slab is 23 cm × 17 cm × 4 cm
Density = mass/volume
Volume of a cuboid shape is equal to, V = 23 cm × 17 cm × 4 cm
V = 1564 cm³
Density,
or
So, the density of the marble slab is 
.
Density= mass/volume aluminum can= 174 •g/ 4 • cm ^3. =2.76•g•cm ^-3
