Answer:
Morphology and phylogenetics revealed by fossils. Perhaps the strongest evidence to support the Cambrian evolutionary explosion of animal forms is the first clear appearance, in the Early Cambrian, of skeletal fossils representing members of many marine bilaterian animal phyla
Explanation:
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Answer:
0.302 moles
Explanation:
Data given
Mass of Pb(NO₃)₂ = 100 g
Moles of Pb(NO₃)₂ = ?
Solution:
To find mole we have to know about molar mass of Pb(NO₃)₂
So,
Molar mass of Pb(NO₃)₂ = 207 + 2[14 + 3(16)]
= 207 + 2[14 + 48]
= 207 + 124
Molar mass of Pb(NO₃)₂ = 331 g/mol
Formula used :
no. of moles = mass in grams / molar mass
Put values in above formula
no. of moles = 100 g / 331 g/mol
no. of moles = 0.302 moles
no. of moles of Pb(NO₃)₂ = 0.302 moles
Answer:
C.) No. of electrons
Explanation:
A.) is incorrect. The atomic number represents the number of protons in an element. Nitrogen (N) and sodium (Na) always have a differing amount of protons.
B.) is incorrect. The mass number represents the number of protons and neutrons in an element. The number of neutrons and protons are specific to each element (disregarding isotopes). When elements ionize, these amounts are not altered.
C.) is correct. When an element becomes an ion, the number of electrons change. When nitrogen gains 3 electrons and sodium loses 1 electron, they end up having the same number of electrons (10).
D.) is incorrect. When elements ionize, the number of neutrons does not change. The only way two different elements could have the same number of neutrons is if at least one of the elements is an isotope. Isotopes are two or more atoms of the same element that differ in their amounts of neutrons.
Answer:
9.64g/mL
Explanation:
Given parameters:
Mass of the metal = 106g
Volume of cylinder = 50mL
Volume difference = 31mL - 20mL = 11mL
Unknown:
Density of the metal = ?
Solution:
To find the density of the metal, we use;
Density = 
Density = 
= 9.64g/mL
