T1-T2
40°+273=313-20°+273=293
313-293=20
the final temp is 20°
Answer: St Br2
Explanation: Br has only one valence electrons and Sr has 2 valence electrons this is why we need 2 atoms of Br to for an ionic compound with 1 atom of Sr.
The correct answer is D:
it involves breaking molecular bonds between copper compounds
.
The explanation :
-when we melt a copper it is a physical change because the substance is still copper and have the same shape.
- but for example Burning a copper it is a chemical change. Fire activates a chemical reaction between copper and oxygen.
-The oxygen in the air reacts with the copper and the chemical bonds are broken.
- the chemical change is changing the other compound bonded to the copper atoms.
So, the correct answer is D
A neutral atom in its ground state contains 28 electrons. this element is considered a <span>transition </span>element, and has 8 electrons in orbitals with l = 2.
Electron configuration: ₂₈X 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸ 4s².
l is azimuthal quantum number, l = 2 describes d orbital. There is eight electrons in 3d orbital.
Answer:
5
Explanation:
Given parameters:
Hydrogen ion concentration = 0.00001M
Unknown:
pH of the solution =?
Solution:
The pH is used to estimate the degree of acidity or alkalinity of a solution. To solve for pH of any solution, we use the expression below;
pH = -log [H⁺]
[H⁺] is the hydrogen ion concentration
pH = -log (1 x 10⁻⁵)
pH = -(-5) = 5
