I would say
D. Gravity pulled particles of dust and gas together to form planets.Hope it helped!
Answer:
Discovery of neutron
Explanation:
Until 1932, the atom was believed to be composed of a positively charged nucleus surrounded by negatively charged electrons, after successful discovery of electron by J.J. Thompson and proton by Ernest Rutherford.
In 1932, James Chadwick bombarded beryllium atoms with alpha particles.
As Chadwick had previously seen in experiment conducted by Frédéric and Irène Joliot-Curie, they had bombarded a sample of beryllium with alpha radiation.
Chadwick repeated the experiment and observed an unknown radiation, this showed no deflection what-so-ever.
He repeated this experiment by bombarding other materials, like helium, nitrogen and lithium,
Finally, Chadwick found that this radiation was composed of particles with a neutral electrical charge and had approximate mass of a proton.
This particle was then known as the neutron.
The answer is C. SiO2 :)))
The given complex Ion is,
[Co(CN)₃]³⁻
In complex compounds the Positive part is named first, followed by name of Negative part. In given case there is no Positive part. So, we will name the Negative part.
In Sphere the Ligands are named first. In this case there are 6 CN⁻ ligands. As CN⁻ (cyanide) contains a negative charge so the -ide is replaced by -o. i.e. Cyanide → Cyano. Also, Hexa is placed before Cyano as there are 6 CN⁻ Ligands.
So,
Hexacyano
After that Chromium metal is named. As there is a negative charge on the sphere, so the -ium in Chromium is replaced by -ate.
i.e. Chromium → Chromate. And the oxidation state of Cr is written in Roman. Hence,the name is as,
Hexacyanochromate (III) Ion
