A potassium atom has 19 protons and 19 electrons, plus 20-22 neutrons.
A rubidium atom has 37 protons and 37 electrons, plus 46-50 neutrons and so is bigger.
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Rb is rubidium, O is oxygen. They will combine to form Rb2O which is called rubidium oxide.
it means right back..
When grading copper cents, there are three main subgrades: BN (brown, a tarnished cent) RB (red-brown, a cent that has began to tarnish) and RD (red, an untarnished cent) out of all of these, collectors will sometimes pay a premium for RD or RB cents because they are much more attractive. However, keep in mind that most slabs aren't airtight and your RB or RD cent may very well eventually tarnish into a BN cent, so my advice is not to pay a premium for the colour designation but rather focus on the true grade of the coin (expressed in a number from 1 being barely recognizable to 70 being perfection)
The "10 Rb" marking inside a gold ring typically indicates the ring's gold content and alloy composition. "10" refers to the karat, meaning the ring is made of 10 karat gold, which contains 41.7% pure gold and 58.3% other metals. "Rb" could refer to a specific alloy or production mark, but it's less common and may require additional context or manufacturer information for precise identification. Always consult a jeweler for detailed insights regarding markings.
Train A is going 60 miles per hour Train B is going 70 miles per hour Let rA = x, then rB = x + 10, and t = 3, then trA + trB = 390 3x + 3(x + 10) = 390 3x + 3x + 30 = 390 6x = 360 x = 60 x + 10 = 60 + 10 = 70