Answer:
See explanation and image attached
Explanation:
Yttrium has many isotopes, the lowest mass number of Yttrium is 89Y.
Recall that electron capture converts an electron into a proton and then into a neutron with a consequent emission of a neutrino (v).
In electron capture, the mass number of the daughter nucleus remains the same as that of the parent nucleus while the atomic number of the daughter nucleus is less than that of the parent by one unit.
Answer:
a. BH₃
Explanation:
According to the octet rules, atoms reach stability when are surrounded by eight electrons in their valence shell when they combine to form a chemical compound.
From the options, the only compound in which the central atom does not meet the octet rules is BH₃. The central atom is boron (B), which has 3 electrons in its valence shell. When B is combined with hydrogen (H), 3 electrons from the 3 atoms of H are added. The total amount of electrons is 6, fewer than 8 electrons needed to meet the rule.
hope this helps
The
Earth is composed of four different layers. Many geologists believe
that as the Earth cooled the heavier, denser materials sank to the
center and the lighter materials rose to the top. Because of this, the
crust is made of the lightest materials (rock- basalts and granites) and
the core consists of heavy metals (nickel and iron).
<span>The crust is the layer that you live on, and it is the most widely studied and understood. The mantle
is much hotter and has the ability to flow. The Outer and Inner Cores
are hotter still with pressures so great that you would be squeezed into
a ball smaller than a marble if you were able to go to the center of
the Earth!!!!!!</span>
The substance has a higher density than water
