Answer:
1. Lanthanum-139 atom is the stable isotope of lanthanum with relative atomic mass 138.906348, 99.9 atom percent natural abundance and nuclear spin 7/2.
2. In fact, over 80% of electric cars sold globally utilized permanent magnet-based motors in 2019. These magnets are typically made with rare-earth materials such as neodymium and dysprosium, which have a very geographically constrained supply chain.
3. It is the second most reactive of the rare-earth metals after europium. Lanthanum oxidizes in air at room temperature to form La2O3. It slowly reacts with water and quickly dissolves in diluted acids, except hydrofluoric acid (HF) because of formation of a protective fluoride (LaF3) layer on the surface of the metal.
Explanation:
1 m = 0,001 km
1m³ = 0,000000001 km³
278 m³ = 0,000000278 km³ = 2,78×10^(-7) km³
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The atoms of some chemical elements have different forms, called isotopes. These break down over time in a process scientists call radioactive decay. Each original isotope, called the parent, gradually decays to form a new isotope, called the daughter. Each isotope is identified with what is called a ‘mass number’. When ‘parent’ uranium-238 decays, for example, it produces subatomic particles, energy and ‘daughter’ lead-206.
Answer:
C
Explanation
His greatest contribution is the atomic model
Answer:
D . 20 grams reactant U + 3 grams reactant V → 23 grams product W
Explanation:
Law of conservation of mass states:
The mass of a closed system (As a reaction), is neither created or destroyed.
That is, the mass of reactants is equal to mass of products.
A. In reaction A 22g of reactants produce 9g of products. This reaction doesn't illustrates the law of conservation of mass.
B. 10g reactant produce 25g of products. This reaction doesn't illustrates the law of conservation of mass.
C. 19g of reactants produce 180g of products. This reaction doesn't illustrates the law of conservation of mass.
D. 23g of reactants produce 23g of products. -This is the reaction that best illustrates the Law of Conservation of Mass.
