Rare earth metals are a group of 17 elements - lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium - that appear in low concentrations in the ground
Explanation:
Mole ratio of Oxygen to Hydrogen gas = 1 : 2.
If we use 3.0 moles of oxygen gas, we would need 3.0 * 2 = 6.0 mol of hydrogen gas.
However we only have 4.2 mol of hydrogen. Therefore hydrogen is limiting and oxygen is in excess. (B)
3AgNO₃ + Na₃PO₄ → Ag₃PO₄ + 3NaNO₃
Explanation:
AgNO₃+Na₃(PO₄) → Ag₃(PO₄) + NaNO₃
To balance this chemical equation, we can adopt a simple mathematical approach through which we can establish simple and solvable algebraic equations.
aAgNO₃ + bNa₃PO₄ → cAg₃PO₄ + dNaNO₃
a, b, c and d are the coefficients needed to balance the equation.
Conserving Ag: a = 3c
N: a = d
O: 2a + 4b = 4c + 2d
Na: 3b = d
P: b = c
let a = 1; d = 1
b = 
c = 
Multiplying through by 3:
a = 3, b = 1, c = 1 and d = 3
3AgNO₃ + Na₃PO₄ → Ag₃PO₄ + 3NaNO₃
Learn more:
Balanced equation
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Specific activity is the activity per unit mass of a radionuclide and is a physical property of that radionuclide. Activity is a quantity (for which the SI unit is the becquerel) related to radioactivity, and is defined as the number of radioactive transformations per second that occur in a particular radionuclide.
How do you find the specific activity of an isotopes?
- Activity = λN.
- = (0.693/8 days) x (1/86,400 sec/day) x (3 x 1017 atoms)
- = 3 x 1011 atoms/sec I-131.
- = 3 x 1011 dps I-131.
<h3>What is the specific activity of Co 60?</h3>
The average specific activity of 60Co in continental aquatic sediments is in the region of 1 Bq. kg-1 dry weight (Eyrolle et al., 2008). Cobalt distribution in the abiotic compartments of continental aquatic systems is characterised by the strong affinity of the element for sediment.
Learn more about specific activity of isotopes here:
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