The choices here are:
<span> a. harder c. more dense b. shinier d. more reactive
The answer is "harder".
The Moh's Scale is also known as the </span><span>Mohs scale of mineral hardness. This scale is basin gon the ability of one certain material to visibly scratch another material. 1 Talc 2 Gypsum 3 Calcite 4 Fluorite 5 Apatite 6 Feldspar 7 Quartz 8 Topaz 9 Corundum 10 Diamond.</span>
The correct answer is Strontium-90.
Strontium-90 breaks down into yttrium-90.
Strontium-90 is a radioactive isotope of strontium. It undergoes β− decay into yttrium-90. A decay energy of 0.546 MeV is also released.
⁹⁰₃₈Sr -> ⁰₋₁e + ⁹⁰₃₉Yr
Beta particle has the charge and mass of an electron. Upon the release of a beta particle, the mass number of Sr remains unchanged but the atomic number of Sr increases by 1. As a result both Sr and Yt have mass number 90, however, Sr and Yt have atomic numbers 38 and 39 respectively.
The polar characteristic of water helps it form strong bonds with other water molecules.
<h3>What is polar structure?</h3>
A polar molecule is a molecule in which one end of the molecule is slightly positive, while the other end is slightly negative.
The attractive force between water molecules is a dipole interaction.
The hydrogen atoms are bound to the highly electronegative oxygen atom (which also possesses two lone pair sets of electrons, making for a very polar bond).
Hence, option D is correct.
Learn more about polar bonds here:
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Answer:
b. HCOOH/ NaHCOO.
Explanation:
A buffer system may be formed in one of two forms:
- A weak acid with its conjugate base.
- A weak base with its conjugate acid.
Chose the pairs below that you could use to make a buffered solution.
a. HCI/NaOH. NO. HCl is a strong acid and NaOH is a strong base.
b. HCOOH/ NaHCOO. YES. HCOOH is a weak acid and HCOO⁻ (coming from NaHCOO) is its conjugate base.
c. HNO₂/H₂SO₃. NO. Both are acids and they are unrelated to each other.
d. NaNO₃/ HNO₃. NO. HNO₃ is a strong acid.
