• Chemistry Doubt?

    At which temperature, in K, assuming constant pressure, is the volume of a fixed mass of gas at 127 °C doubled? Can someone explain the reasoning behind the answer? Thanks in advance!
    At which temperature, in K, assuming constant pressure, is the volume of a fixed mass of gas at 127 °C doubled? Can someone explain the reasoning behind the answer? Thanks in advance!
    11 answers · Chemistry · 2 weeks ago
  • Prime pairs?

    Best answer: The proof is by induction on n. For n = 1 the result is trivial. {1+2} = 3 For n > 1, let p be a prime satisfying 2n < p < 4n. Since 4n is not prime we have p = 2n + m for 1 ≤ m < 2k. Pair 2n with m, 2n−1 with m+1, and continue up to n+⌈k⌉ with n+⌊k⌋ (this last is a valid pair since m is odd).... show more
    Best answer: The proof is by induction on n.

    For n = 1 the result is trivial.
    {1+2} = 3

    For n > 1, let p be a prime satisfying 2n < p < 4n. Since 4n is not prime we have p = 2n + m for 1 ≤ m < 2k. Pair 2n with m, 2n−1 with m+1, and continue up to n+⌈k⌉ with n+⌊k⌋ (this last is a valid pair since m is odd).

    This deals with all of the numbers in {m, m+1, …, 2n}; the inductive hypothesis deals with {1, 2, …, m−1} (again since m is odd).
    6 answers · Mathematics · 2 weeks ago
  • How would you prepare for the following emergency? The gravitational bond between earth and sun disappears and a black hole takes its place?

    Best answer: If that truly did happen, events on Earth would be so overwhelming that no form of preparation would make any difference.
    Best answer: If that truly did happen, events on Earth would be so overwhelming that no form of preparation would make any difference.
    31 answers · Astronomy & Space · 2 weeks ago
  • Multiply 45 times 30?

    20 answers · Mathematics · 2 weeks ago
  • Now you put on your glasses and tell me if South America is not connected to the Antarctic by an isthmus?
  • Will hippos let you pet them?

    23 answers · Zoology · 2 weeks ago
  • What is the difference between the telescope and the microscope?

    Best answer: Both need to produce their image at a workable distance from the objective lens. With the telescope the object is near infinity so the image is near to the objective lens' focal point. With the microscope the object is placed close to the focal point so the image is near to "infinity" relative to... show more
    Best answer: Both need to produce their image at a workable distance from the objective lens.
    With the telescope the object is near infinity so the image is near to the objective lens' focal point.
    With the microscope the object is placed close to the focal point so the image is near to "infinity" relative to that.

    Hence short focal lengths close to the object for the microscope, long focal lengths close to the image for the telescope.
    Otherwise the geometry and design are identical.
    13 answers · Engineering · 2 weeks ago
  • Do race and ethnicity really have no DNAs and genetic bases in biology?

    Best answer: Humans originated in Africa, and all non-Africans are descendants of a small number of Africans who migrated out of Africa 60,000-70.000 years ago. Many of these people still look very much like Africans because they changed little since they migrated out of Africa, because their ancestors ended up in places with... show more
    Best answer: Humans originated in Africa, and all non-Africans are descendants of a small number of Africans who migrated out of Africa 60,000-70.000 years ago. Many of these people still look very much like Africans because they changed little since they migrated out of Africa, because their ancestors ended up in places with similar climates as Africa, such as New Guinea, SE Asia, Papua and Australia

    Europeans, and NE Asians, OTOH, have changed because they adapted to cold climates by evolving straight hair, lighter skin tones, shorter arms and legs, more rounded torso, taller and narrower nose bridges, thinner lips, more facial and body hair, and more fat under the skin. The Europeans and NE Asians (China, Japan and Korea) descended from Africans who stayed in Central Asia for about 20,000 years before migrating again. Central Asia is cooler than Africa, so some of these adaptations to cold climates first evolved in Central Asians. Europeans and NE Asians therefore are similar because they inherited some features from their shared C. Asian ancestors. and they then evolved similar features independently by adapting to cold climates of the last ice age. .

    Further, humans have not stopped migrating since then, and we have NE Asians migrating south to interbreed with SE Asians and their descendants have a mix of cold and warm adapted traits and a mix of genes. Central Asians and Europeans too have migrated to parts of East Asia. Europeans also migrated to the Middle East and North Africa, and later some of the Middle East people migrated back to Europe and to North Africa. For example, Italians from the southern part of their country are more closely related to people from Turkey, Iraq and Iran then they are to the northern Italians, who are more closely related to western Europeans like Germans, British and French. Because of such mixing it is difficult to find genes or traits that can be used to identify the people from one region vs. another. What we do have are mitochondrial DNA and Y chromosome markers that can trace a person's ancestor to a particular region, but these markers cannot be used to define races, since they do not produce the raical characteristics thaqt people notice.

    Because scientists cannot come up with any good way to divide the human species into different subspecies or races, they have stopped trying.
    6 answers · Biology · 2 weeks ago
  • Can someone please help with hard math question?

    A pencil consists of a cylinder with a cone on top. The total volume is 7.25 cm^3. How long is the pencil?
    A pencil consists of a cylinder with a cone on top. The total volume is 7.25 cm^3. How long is the pencil?
    8 answers · Mathematics · 2 weeks ago
  • Compare the size of Eris to Pluto?

    Eris: 2326 km Pluto: 2377km find relative difference
    Eris: 2326 km Pluto: 2377km find relative difference
    12 answers · Astronomy & Space · 2 weeks ago
  • Will Trump be throwing out paper towels for the east coast?

    Best answer: Yes. Custom made Orange ones.
    Best answer: Yes. Custom made Orange ones.
    9 answers · Weather · 2 weeks ago
  • Are Opossums dangerous?

    12 answers · Zoology · 2 weeks ago
  • Is it possible there are more stars in the universe than people on this planet?

    Best answer: Oh yes, certainly there is, the universe goes on forever.
    Best answer: Oh yes, certainly there is, the universe goes on forever.
    6 answers · Astronomy & Space · 2 weeks ago
  • Is it inaccurate to report the weight of a sample to be <0.00 grams? (chemistry lab)?

    i was weighing a very small sample of a compound that i produced from an experiment. when i weighed it on a top-loading balance, it did not read at all and it just showed 0.00g my fault for not using a more sensitive balance but with the data that i have, would it be inaccurate to say that it weighs <0.00... show more
    i was weighing a very small sample of a compound that i produced from an experiment. when i weighed it on a top-loading balance, it did not read at all and it just showed 0.00g my fault for not using a more sensitive balance but with the data that i have, would it be inaccurate to say that it weighs <0.00 grams? or should i say <0.01g? i just don't want the <0.00 grams to be mistaken as a negative number when i'm just trying to say that it may have weighed 0.005 grams or something.
    11 answers · Chemistry · 2 weeks ago