Answer:
Group 2A (or IIA) of the periodic table are the alkaline earth metals: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). They are harder and less reactive than the alkali metals of Group 1A.
Explanation:
Answer:
19.8m/s
Explanation:
Given parameters:
Mass of the ball = 10kg
Height of the rail = 20m
Unknown:
Velocity at the bottom of the rail = ?
Solution:
The velocity at the bottom of the rail is its final velocity.
Using the appropriate motion equation, we can find this parameter;
V² = U² + 2gH
V is the final velocity
U is the initial velocity
g is the acceleration due to gravity
H is the height
the ball was rolled from rest, U = 0
V² = O² + 2 x 9.8 x 20
V = 19.8m/s
Answer:
-514 kJ/mol
Explanation:
The bond enthalpy which is also known as bond energy can be defined as the amount of energy needed to split one mole of the stated bond. The change in enthalpy of a given reaction can be estimated by subtracting the sum of the bond energies of the reactants from the sum of the bond energies of the products.
For the given chemical reaction, the change in enthalpy of the reaction is:
Δ
[2(409) + 4(388) + 3(496) - 4(630) - 4(463)] kJ/mol = 818 + 1552 + 1488 - 2520 - 1852 = -514 kJ/mol
