Only considering attested works, the number is 44 with the following distribution: piano (27), violin (5), horn (4), flute (1), bassoon (1), harp and flute (1), oboe (1), clarinet (1) for a total of 41 to which we can add 3 more: 1 sinfonian concertante for violin and viola 1 sinfonia concertante for oboe, clarinet, horn and bassoon 1 flute concerto (arrangement of bassoon concerto)
W.A. Mozart wrote 27 concertos for Piano and Orchestra.
Wolfgang Amadeus Mozart wrote many Piano Sonatas, Concertos, Duets, Trios, etc. There are probably anywhere between 200-300 piano pieces written by Mozart.
Which one? There was Mozart's Concerto, Piano Concerto, Tchaikovsky's Concerto, Many more I can't name. but Concerto in G minor, You'll have to find out for yourself (sorry). =/
Mozart composed for nearly every combination of instruments of that time. Examples are works for: piano and orchestra; orchestra; voice and orchestra; piano; string quartet (2 violins, a viola and a cello), string quintet (2 violins, 2 violas and a cello), piano and violin, clarinet and orchestra, flute and orchestra, and many, many others.
He wrote 5 piano concerti aswell as 2 piano concerti during his youth, one violin concerto which he later transcribed for piano and orchestra and he composed one 'triple' concerto for piano, violin and cello. He wrote a number of pieces for solo instrument and orchestra and an oboe concerto which was lost by publishers in the 1840's.
The asker did not specify a composer, but I'm going to assume that he/she meant Mozart, as he is the only composer still famous today to have written so many piano concerti. He wrote his twenty-first, like most of his piano concerti, for himself to perform. It was written in the space of only four weeks, immediately following the premiere of his great D minor concerto, the twentieth--the two are one of his many pairs of great works of antithetical temperaments, something Mozart seemed to enjoy challenging himself to do.
The list is rather long, and includes Piano Concerto No.s 1-27, Concerto for Two Violins, Violin Concerto No.s 1-5, Flute Concerto No.s 1 & 2, and many more. See related links for a more comprehensive list.
626 cataloged by Kochel. Since Kochel's count, we have discovered more. So about 1,000
32 Beethoven actually wrote 38 piano sonatas, although 6 of them are without Opus numbers (WoO). True but no.33, 34 and 35 had ' to the Archbishop elector of Cologne Maxim. Frederick' and no. 36 had 'to Eleonore von Breuning' written next to them in brackets in my book.
He wrote 25 in a major key and only 2 in a minor key.
Three