Answer:
Isotopes are the elements having the same atomic number i.e same number of protons which in turn is equal to same number of electrons. Number of protons and electrons are equal as the atom is electrically neutral. So, the only option is A.
I hope it helps you !
Answer:
Explanation:
In 1789, Antoine Lavoisier published a list of 33 chemical elements. Although Lavoisier grouped the elements into gases, metals, non-metals, and earths, chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads (groups of three) based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together as being soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third.[19] This became known as the Law of Triads.[20] German chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all.[19]
Answer: C. Electron degeneracy pressure depends on the speeds of electrons, which approach the speed of light as a white dwarf's mass approaches the 1.4-solar-mass limit.
Explanation:
Answer:
0.70 s
Explanation:
Potential energy = kinetic energy + rotational energy
mgh = ½ mv² + ½ Iω²
For a thin spherical shell, I = ⅔ mr².
mgh = ½ mv² + ½ (⅔ mr²) ω²
mgh = ½ mv² + ⅓ mr²ω²
For rolling without slipping, v = ωr.
mgh = ½ mv² + ⅓ mv²
mgh = ⅚ mv²
gh = ⅚ v²
v = √(1.2gh)
v = √(1.2 × 9.81 m/s² × 1.1 m sin 49.0°)
v = 3.13 m/s
The acceleration down the incline is constant, so given:
Δx = 1.1 m
v₀ = 0 m/s
v = 3.13 m/s
Find: t
Δx = ½ (v + v₀) t
t = 2Δx / (v + v₀)
t = 2 (1.1 m) / (3.13 m/s + 0 m/s)
t = 0.704 s
Rounding to two significant figures, it takes 0.70 seconds.
Answer:
Yes, cause when listener is far away from music source... the listener feels it's pleasant.... but when observer approaches near loudspeaker... sound become unpleasant..........sound becomes noise when frequency crosses 85 Decibels.....so you can say that the voice from loudspeaker also get shrill when the listener reaches the surrounding source......